


and the sea so deep

by venvephe



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alternate Universe, Alternate Universe - Dark, Alternate Universe - Fantasy, M/M, Merlock, Mermaids, mer!lock
Language: English
Status: In-Progress
Published: 2013-03-11
Updated: 2014-04-20
Packaged: 2017-12-05 00:28:15
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 50,650
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/716786
Author URL: https://archiveofourown.org/users/venvephe/pseuds/venvephe
Summary: <blockquote class="userstuff">
              <p>The tales told of all manner of things seen out there, in the open ocean where no land was visible, and only the moon and stars to keep you company at night. They spoke of soft songs and sharp teeth, the flicker of large movement close to the surface of inky water - of chilling laughter, and men gone missing. There were dark things in the dark waters, the whispers said. </p><p>John never thought he would meet one of them.</p><p>A dark, realistic Mer!lock AU.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

  * For [michi_thekiller](https://archiveofourown.org/users/michi_thekiller/gifts).



> Mermaids make for tricky business. I never thought I'd be writing a story about one, but one thing led to another and after half a dozen conversations with Michi, I had the start of something interesting. It's since evolved from there, but it was primarily my love for marine biology and myths as well as Michi's support that got this where it currently is. I've never spent so long in Wikipedia reading about shark biology. I know what viviparous means. I drew mermaid skeletons on pieces of scrap paper. I am striving for a realistic mermaid, here, and maybe I've achieved it. We'll see more as the story progresses.
> 
> For now, this is my first published piece, so please enjoy!

_“I never dreamed the sea so deep,_

_The earth so dark; so long my sleep,_

_I have become another child._

_I wake to see the world go wild.”_

****

\- Allen Ginsberg

 

 

 

 

•

 

John didn't like dark water. Perhaps it was because he wasn't a born-and-bred sailor; perhaps, because he had spent so much time looking up at the dark sky splattered with stars that looking _down_ into dark, unfathomable depths below was foreign and unsettling. It _was_ unsettling, not knowing what could possibly be lurking under the opaque skin of the water, oil-black and slick and gleaming with the reflection of the yellow light pouring from his cabin window.

There were also the stories.

If you spent any time in a seafaring port longer than two hours, you heard the stories. They passed from crewman to barmaid, from steward to soldier, across lips and changing hands as often as gold coins.The details changed, twisted and knotted and folded in on themselves, but that didn't make them any less true, or any less foreboding.

There were dark things in the dark waters, the whispers said. It was easy to talk about in the merry light of a tavern, surrounded by pints and warm candlelight and the comforting human scent that was often lost at sea. On land, it was something you could talk about - could laugh about, even. But not out in the open water, the blanket of night draped over the ship and the eerie quiet seeping into your bones.

The tales told of all manner of things seen out there, in the open ocean where no land was visible, and only the moon and stars to keep you company at night. They spoke of soft songs and sharp teeth, the flicker of large movement close to the surface of inky water - of chilling laughter, and men gone missing.

John didn’t like to pay attention to those stories, but like so many things about this new, oceanic life of his, they had just started leaking in. Overheard conversations collected in his mind over time, layer upon layer of story and myth that built up over the weeks and months, like the steadily deepening tan across the bridge of his nose and the strong line of his shoulders. He could recite many of the popular ones himself, by now, though he didn’t give them much merit. Surely it was the mysterious nature of the sea at night itself that caused these stories to be borne, and nothing else.

Now, staring into the gentle black waves, John wasn’t so sure. His convictions seemed far away, back on the shore they had left behind three days before. The idea of something lurking below wasn’t so strange, when you were peering down at it by yourself, in the dark.

 

 

•

****

Of all the stories that circulated those ports, those people, there were time-and-again favorites that came back like bad pennies. The ever-shifting details caused John to further doubt the validity of them - of course they were absurd in the first place - but he shouldn’t have. Some of them were true.

Cursed treasure was a theme often compounded upon, be it gold or crown jewels, or maybe just the revered map that would lead to such a bounty. Pirate stories were likewise as common and well-told, although John knew some of those were true by the names of the pirates, if nothing else.

No, it was the stories of the monsters and creatures that loomed _below_ the hulls of their beloved ships that made the fine hair at the nape of John’s neck stand on end.

And even among all of these stories - for there were many - only one ever stood out in John’s mind, the only one he would strain to hear over the din of a tavern or shipyard.

It was one of the oldest tales, and it went like this:

 

If you stand on the bow of your ship at the witching hour, on one of those still nights where the moon is but a thin white scar upon the night sky - if you stand with a single yellow lantern and lean over the side of your ship in total solitude, and sing her name like a lover would - then _she_ will come.

The water below you, calm and still and a perfect mirror for the stars and moon above, will churn and ripple as if a large fish is brushing at the surface. The soft circle of light cast by your lantern will flicker. In between one moment and the next, when the lantern’s light has dimmed completely, she will appear - and the lantern will suddenly blaze to life again, and she will be caught in the warm pool of light.

She will look like a young woman, a little pale against the darkness of the sea around her, but the sheen of silver scales trailing down her belly and disappearing into the water will betray her true nature. Her hair will be the color of ink, or dark water, falling in dripping ringlets and curls down her back and across her shoulders. The contrast is striking, the dark hair against the unmarred whiteness of her bare skin, which is wet and slick and goes on, and on, and on.

She will be bare - and undoubtedly you will be drawn to the perfect curve of her skin-silver hip, the roundness of her exposed breasts and the supple pink of her lips - but her eyes will be your undoing. They will be the same crystallized blue of the ocean that draws you to the life of a sailor, and you will drown in them.

The chill of the night will disappear from your fingers as you look down on this strange but beautiful creature, the arc of a fish-like silver tail beating under the water in sinuous, serpentine, undoubtedly sensual movement. She will ask for your name and smile when you give it freely, the dimples in her cheeks distracting you from the sharp edge in her eyes, and the elongating points of her teeth.

She will coax you over the edge of the ship with a song. It is just for you, though it has no words, and it pulls at you heavily until you can’t stand the distance, and you slip off of the deck and into the sea. The water will be warm but her body will be hotter, pressed against yours in the deep, dark water.

You’ll whisper her name when she clutches you tighter in her arms, before her kiss turns to a bite and she drags you, still pliant, below the surface.

_Aeserena._

A storm will come, the next day, one so violent and furious that the water will froth and churn white, and the rigging and sails will rattle like hollow fortune-teller’s bones. The crew will realize, when it passes and the sea is once again flat, that you are gone.

All that will remain is the snuffed-out lantern, now shattered and dripping on the waterlogged deck, wax hardened in the pattern of white veins from the solitary, dead candle.

 

 

•

****

By some strange miracle of posterity, more of the details synchronized in this story than in any other. Perhaps that was what John found most unusual. For all that seafaring folk loved to talk and share and embellish their yarns over mead and bread, every version of this tale featured the dark hair, the ice-blue eyes, the silvery scales and the sibilant, ancient name. _Aeserena_ , mother and queen of the Mer, creatures with the faces and torsos of human women, but with the shining, scaled tails of fish.

Something disturbed the calm waves as John watched, looking down from his cramped cabin room. It was just a flicker of movement, of something reflecting his light other than the liquid surface of the ocean. John shook his head and blinked, finally sleepy. It was probably just a fish, or a curious dolphin swimming close to the ship. It was no use letting his mind run away to the fanciful tales he had heard in port.

He snuffed his lone candle and settled into his bunk, the ship’s gentle rocking and the deep sighing creaks of the wood lulling him back under, to sleep.

 

 

•

 

There had been a single light streaming from the ship for four nights now. The lamp appeared at least two hours after moonrise, never more than five; and indeed, it had been there, like an eye winking on the sleek surface of the hull, for each of the past four nights. It flickered away before sunrise.

 

 

•

****

The _Zephyr_ was a good ship, only a frigate of moderate size, but she was clean and well-kept and she had become John’s home, in the past months. He’d never have believed it, that he could feel at home on a ship - a moving, breathing thing of masts and sails and busy, ant-like crew - but all for that he had never felt the pull of the sea before, he could now see how it could so easily draw you in.

Lestrade was a good captain, too, just and knowledgeable and as loyal to his crew as any of them were to him. Working under a moral captain had been one of the few points on which John had been unwilling to compromise, when his life had taken an unexpected turn and it was clear he’d have to make a living for himself at sea. He'd been lucky to find the _Zephyr_ , a modest privateer that spent most of its days patrolling the coastlines and shallow Caribbean seas to keep the peace. That she was in desperate want for a ship doctor had been such a stroke of luck that it had felt like fate.

It had, admittedly, taken him weeks to settle into his new place. The gentle rolling and pitching of the ship was foreign at first - and his limp hadn't helped with that matter - but as John well knew, humans could adapt themselves to anything, and soon the captain had been slapping him on the back in encouragement for having so quickly found his sea legs. The names started falling into place after that: not only of his fellow crewmen, but of the myriad parts of the ship, jib and topmast and mizzen and sails; their ports of call, strung together like a constellation by their many journeys when plotted on a map; and the sea lore, maybe most interestingly of all.

The crew didn't like to tell tales on board their own ship - sailors were nothing if not superstitious, John learned - and Lestrade, ever pragmatic, had made it clear that he didn't want his crew filling each other's heads with such nonsense when they should be focused on minding their posts. This was all well and good with John; he had never bought much into superstition, though it was with some amusement that he joined the crew’s regular cajolement of the second mate, who liked to think his nautical prowess extended to predicting the week’s weather. There were plenty of other stories to tell, after all, besides the supernatural ones. John's natural talent for storytelling had ensured that he was accepted into the fold seamlessly after only a few weeks on board. Now, John couldn't see himself any happier, or anywhere else.

 

 

•

****

If it weren't for the nights, John would have called his life on board the _Zephyr_ ideal - better than, considering his luck. Between waking up - twisted in his bed sheets and sweating and shaking off the nightmares - and the restlessness that kept him from falling asleep in the first place, John dreaded the setting of the sun and the steady darkening of the sky. He wasn't much fond of dawn, either, as the first rays of sunlight heralded a new day and, more often than he liked, the end of another night of unsuccessful rest. He managed to get a few hours here and there, sometimes a nap mid-afternoon if it was a calm day at sea, but it was wearing on him to go for so long without decent sleep.

It was the fifth night on which he'd been unable to sleep that he made his way up to the main deck with a small lantern. Waiting out the insomnia in his tiny cabin hadn't done him any good on the previous nights, serving only to increase his frustration and boredom, feeling trapped by his room as well as his body.

It was cooler, under the stars, with a soft breeze that made the heavy fabric of the sails sigh and sway. They had made good progress the previous day, the wind fortuitously filling their sails and carrying them farther than Lestrade had expected to manage on their route. For that reason, he had anchored them on a coastal sand bar for the night, giving the crew with the midnight shift a much-needed break. The deck was eerily empty as John wandered onto it, silent and barefoot.

John settled himself on a railing on the aft of the ship, the whole of the decks spread out before him in the warm glow of the lantern. Besides his solitary light, the decks were illuminated only by the soft starshine; it was a new moon, so the thick band of stars striping the night sky wasn't masked by the moon's face. It made a white-purple halo around the _Zephyr_ in the perfectly flat surface of the sea. The ship appeared to be bathing in stars.

John was tempted to snuff out his lantern and bask in the light of the night sky, but he didn't want to startle anyone if another crewmate came up on-deck; he had an odd enough reputation without being caught lurking in the dark. He let his eyes wander, the deep sighing of the ship like the snoring of a large beast. From his pocket he pulled a small clam-shell compass, carved delicately from deep red mahogany, and traced the patterns absentmindedly. He placed his other hand on the worn deck railing. The cool, smooth wood under his palms was comforting in its own way; John smiled wryly at the sailorly habits he'd clearly started to develop. His mum would laugh to see him, caressing the weathered oak of a sailing ship and the carved compass, for all he'd always said he would never go to sea.

He picked out the constellations as he tried to settle his mind, to let the easy rocking lull him to sleepiness. _Ursa majoris, ursa minoris. Sirius, the dog star. Cassiopeia._ He had always had a wonderment of the stars, though, and while it didn't make him more tired, he relished the unspoiled view of the night sky all the same. _Cygnus the swan. Hercules._

A faint splash pulled him from his reverie.

John looked down from the sky with widened eyes, the fine hair on the nape of his neck rising. A shiver ran through him in spite of the mild calm of the night. The noise of stirred water was brief, and had come from over the starboard side: from below, in the otherwise still shallows. Already a serene silence was enveloping the ship, and John's ears rang with the remembered noise that he was suddenly not sure he had truly heard. He tucked the compass back into his pocket, swallowing hard.

He reached out for the lantern, holding it over his head as he studied the star-lit decks for movement. Jaw clenched, he waited in absolute stillness. Nothing more came.

The weather-worn wood was cool under his bare feet as John hoisted himself upright. He approached the starboard side of the ship carefully, taking measured steps to prevent the boards from creaking underfoot. When he reached the quarter-deck railing he grasped it in a white-knuckle grip, leaning over the edge to swing the lantern in a slow arc that illuminated the water below.

The warm halo of light turned the water green-blue and hid the stars; John's concerned face reflected back up at him. The surface was mirror-like, his reflection perfect, but as he watched, something just out of the reach of the lantern-light disturbed the sea and ripples warped his image.

John stepped onto to the main deck, towards the mid-ship break in the wood rails. This time, he held the lantern aloft and stretched further towards the dark water.

The light caught on a pair of eyes, reflecting brightly in the light like a cat's. John startled. The wide, round pupils shone pink, shrinking as the light hit them, and more of the pearlescent irises ringed them. John couldn't say what was more stunning; the color of the unexpected eyes, or that something was peering back at him from the sea in the dead of night. As he watched, the eyes blinked and drew closer.

What swam its way into his pool of light knocked the breath out of John's chest. The bright, almond-shaped eyes belonged to a human face: strong brows and sharp cheekbones and lush mouth and pale skin. A dark tangle of curls was slicked against its brow, and as it approached, it drew further out of the water to reveal sinewy arms, a lean, flat chest, and narrow hips where the lily-white skin became the glistening silver of scales.

John's realization came with a sickening lurch of his stomach.

He was looking at a Mer.

John gaped, taking in the form of the creature, and his first thoughts were, _Well, you can't trust sea stories to get all the details right._

The Mer in the warm shallows below him - for that was undoubtedly what the creature was, John told himself - was clearly male, where all of the hundreds of variations of the stories John had ever heard featured a female of this mythical species. This creature bore no luscious curves other than the warm pink of his full lips; he was lean and muscled in a way that belied wiry strength. The muscles in his shoulders drew taut, and John caught a glimpse of horizontal striations on his neck which could only be gills. The Mer found an outcropping of coral-studded rock in the shallow water, and braced himself against it so that most of his torso was out of the water as he continued to watch John.

That was another thing: John had not called this creature's name, though he was suddenly quite aware that he was aboard a ship, on a dark and moonless night with a single lantern. Perhaps more was true to the tales than he had given credit.

John's hand didn't shake, and he swallowed thickly. He remembered, with aching clarity, the grim endings to the stories involving the Mer. He was determined to stay where he was, safe on board the familiar decks of the _Zephyr_ , and not get lured to the waves. His pulse was throbbing in his throat, his heart beating a rapid staccato against his ribs in nervousness. As he stayed still, tense but solid and unwavering, the Mer's expression drew from curiosity to amusement.

"Well," the Mer said, in voice that was deep and melodic, "This is the fifth night."

John stared, surprised. As if anything else about this incredible encounter could shock him. "How did you...?"

The Mer blinked up at him with those pale eyes, and a strange chill passed up John's spine; even though he was the one perched high above, on the deck with the sole source of light, he felt exposed, vulnerable and transparent before this creature.

"Your ship is passing through my territory. I have been following it these past four nights," the Mer replied, tilting his head in the direction of the name painted along the ship's dark bow. The motion caused the inky curls to part, revealing the curve of a human ear, but extended further in a soft point and fringed with a delicate membrane - a small fin, John realized.

"This is the fifth night you have had a light shining from this ship, though it is the first of which you have come up onto the deck," he elaborated, eyes pinning John where he stood. A smile started to curl at the corner of his lips, "And it is the night of no moon."

The hairs on John's arms stood on end. Indeed, that was a central part to the ritual in the stories. The dark-haired Mer was staring at him expectantly, waiting for his answer.

"Yes, um, that it is,"John said, once he had found his voice, "I'm sorry if we've been trespassing in your waters, and I apologize if my light has disturbed you, but I didn't - um. I didn't call you here. Sir."

Below the surface, the Mer's silver tail slowly waved, powerfully muscled but lean like the rest of him. It glinted like the gold of sunken treasure in John's lamplight.

The Mer's eyes narrowed slightly. "What is your name?"

John was thrown into the memory of being five, suddenly; of his mother spreading honey and jam on thick slices of bread for him to eat and telling him stories in the late morning light. _Words are powerful for fairy-folk_ , she’d said. _There is magic in names, too. Never tell your true name to a Fay; they can thread it into their magic, and use it against you._

John swallowed. "James," he said, trying to keep his voice as steady as his hand. Something about his reply must have amused the Mer, though, because it was smirking at him, his cupid's bow mouth pulling at the corners and his eyes gleaming.

"James," he rolled the name on his tongue, and John had no doubt that if he had given his true name, hearing it in the resonant baritone of the Mer would have had quite a dangerous effect on his resolve. "How curious, James. What have you been doing with your light, so late these past four evenings?" The Mer blinked up at him, tail continuing its languid, undulating movements under the water. Something stirred low in John's gut at the velvet tones, at the sinuous movement of silver-gold scales.

"Insomnia," John said, matter-of-fact, "I don't sleep as I should. Not because I do not wish to, but because I can't.”

The Mer's smile was widening, “And so you have been awake in your small room, awaiting the dawn to reprieve you. Yet tonight is different.”

John’s arm was beginning to tire, so he pulled in the lantern from where he still had it outstretched, and set it on the waist-high handrail at his hip. The Mer looked even more ethereal in the half-darkness of the lantern and star-light, eyes pale and bright and flecked with silver.

“Yes,” John tilted his head, conceding the truth, “Even more so, now.”

“Yes, indeed,” the Mer grinned.

They were silent for a few beats, watching each other with mutual curiosity, and not a small amount of wariness on John’s part.

“What causes a healer to not sleep?” the Mer said, breaking the silence in a musing tone, “Surely you have been at sea long enough to no longer miss your home, even if it was an unexpected and recent change. You make landfall often enough to get your fill of dry land.”

“Three months,” John found himself saying, “Land is always a welcomed sight, indeed. And I am learning to love the sea.”

“Yet you have never felt a real pull to it before,” the Mer tilted his head. The gossamer membranes of his ear-fins were iridescent, green-gold-pink. “Before tonight.”

John paused again, and played the conversation over once in his mind. “How did you know all of that? That I’m a doctor?”

The Mer smirked up at him, tail fanned under the water, and said nothing. John shook his head at the lack of reply, frowning.

“I’m not sure I believe you’re real,” he said.

The Mer didn’t look perturbed at that.

“You could come and get a closer look,” he smiled, lazy and seductive, shoulders rounding as he leaned, making a perfect S with the curves of his naked back and tail. John felt his face heat. In spite of the display, he needed no reminder of where he was, or who he was talking to, though the both the invitation and the implication were tempting and crystal-clear.

“To be honest,” John said, “There is no sodding way I’m getting off this ship and into the water, thanks.”

The Mer stilled.

“I do know how the stories go,” John continued with a small shrug.

The Mer blinked owlishly, John's response clearly unexpected. His entire demeanour changed as John watched. The sensual air surrounding him sloughed off, shedded from him effortlessly like the droplets of water beading on his skin. The arch of his back straightened; his tail stilled in the water and his brows drew downward into a frown. His chin tilted as he peered up at John, the white column of his neck extended this time not purposefully seductive, but as a means of examining him further.

“You don’t seem very afraid.”

“You don’t seem very frightening,” John replied evenly, though his heart’s tempo had increased in his chest. The Mer’s smile sharpened at his words.

“That, _James_ ,” the deep voice dipped lower, “Is entirely intentional. How else am I to lure you humans into the water, if not by appearing something _other_ than frightening?”

The words were out of John’s mouth before he could stop them. “You sing.”

The Mer snorted, “My brethren do. I do not.”

John’s brow furrowed; was that a personal preference, or another instance of falsehood in the stories? The stories had never mentioned male Mer, to begin with. Certainly there were other embellishments that held no truth, though he now had a feeling that there were grains of truth in each of the versions he had heard.

“I can,” the Mer amended, as if sensing John’s confusion, “I can weave the Song as well as any Mer. I choose not to.”

“Why?”

John got the feeling that he was starting to ask the right questions; the Mer looked radiant in his sly amusement, cat-like eyes narrowed dangerously.

“I don’t need to.”

The silence between them was tense and pregnant with the questions John wanted to ask, fighting himself on whether or not to hold his tongue. Continuing this conversation, he knew, was increasingly dangerous. There were no stories of sailors encountering the Mer that ended with the sailor alive and the Mer unfed or alone.

And yet: this was the most exciting thing to happen to him in all his time aboard the Zephyr, in his new life at sea.

“How?” he asked, his voice edging on breathlessness.

“You asked me that earlier, when I mentioned that you were a healer, and that you had not expected your life to take the turn which led you to take this post aboard a ship. You remember?” The Mer waited for John’s nod before continuing, “I did not know; I observed, and from what I observed I concluded those facts.”

“Yes, but - how? In this low light?”

The Mer preened. “Even so.”

“I must be an easy study, then, to be so clear to you from up so high,” John said.

“Only because I know what to look for,” the Mer smiled, indulgent in what was clearly his source of pride, “To get into the mind of one’s prey - what better way to convince him that he should leap into the sea?”

John shivered. _Prey._

“I continue to maintain that I won’t be jumping in,” John kept his voice steady. He hooked one of his bare feet through the gap between two of the railing posts, curling it against the smooth wood to anchor himself.

The Mer had seen his action, correctly interpreted its cause - John was nervous. His smile was more bite, now, more teeth. Shark-like.

“The way you hold yourself - strong. Confident. You are not afraid of being out here, in the dark of a moonless night. Even if someone were to find you, then, it would cause no alarm. You are trusted among your fellow men. Who has the implicit trust of all? A healer; the one who cares of the injuries of others, who is a natural caregiver and confidante.”

The Mer gave him an appraising once-over, more obviously this time. “You walk with a limp, but forget it as you stand. An injury that you can forget? Not a true wound...or, perhaps, one that is long past though the pain remains,” he shook his head, “I cannot tell from here, though I expect that like the tremor in your hand, the pain is borne of your mind, not your body.”

It felt as if John’s heart was clogging his throat as he was flayed open and exposed by the sharp truths the Mer was listing, unerringly, one after the other.

“And here you are, on the night of no moon with a solitary lantern, unable to sleep. My presence surprised you, but not enough for you to raise an alarm. You have heard stories of us, and while you are wary of the danger I pose, you are curious as well. Perhaps you are attracted to the danger, or to the inherent sexuality my kind presents.” John’s pulse throbbed, a surge of heat pooling in his gut again. “Either way, it has led you into this conversation. Am I wrong?” The smile was still sharp, still smug, on the Mer’s knowing face. He was enjoying this.

“That’s what you do, then, isn’t it?” John asked, feeling something akin to anger start to burn, “You find the opportune moment, someone alone; you observe them and then tell them what they want to hear to get them to come to you. Into the water. And then -” He stopped, a chill going up his spine once more, and a churning sick in his stomach that he couldn’t blame on a rough sea. He’d gotten comfortable, somehow, over the course of his conversation with this creature. It was an unsettling reminder, the thought that the Mer indeed used their talents to seduce men off of their ships in order to consume them. But it was a reminder that he needed, nonetheless. He couldn’t afford to let the beauty of the Mer’s form and the heady rumble of his voice distract him. It would have been his undoing, if he had. _Steady, John Watson,_ he thought.

“Yes,” the Mer must have sensed the change in course his thoughts had taken, because the smile had fallen from his face, “ _And then_."

His head was tilted curiously to the side still, but his eyes had darkened. John clenched his jaw. He didn't have any idea how he would hold firm against the magical pull of the Mer Song, if it came to that, but damned if he wouldn't try, if it came to that. But perhaps there was a way to come out of this intact and unscathed.

“I admit,” the Mer finally said, “The course of this evening has not followed what I expected, and that in itself makes it as unusual as yours.”

“Oh?” John asked. His throat felt dry and he dug his fingers more firmly into wood of the railing.

“You are correct, of course, in the way that I use my ability to lure in my prey,” the Mer shifted on the rock, the line of his spine arching as he stretched, “But it is more than rare that my innate charm does not take root in the mind. You have rebuffed me, and that...is _fascinating_.”

The Mer’s gaze was piercing and almost hungry. He was still curious, keenly so, but rather than angry he appeared to be thrilled at the prospect of such an extraordinary encounter - of John.

The sight of him, delighted in this small mystery, lit an idea in John’s mind.

“If you do, indeed, find me so fascinating...” he said, locking eyes with the Mer, “Then I have a proposal for you.”

The Mer stilled, staring. Then his lips twisted into a smirk.

“I’m listening.”

“I think -” John licked his lips, “I think you’re still planning on getting me into the water somehow, to eat me, before dawn. You approached me in the first place so that I would become your meal, and leaving me alive would be dangerous if I told anyone else about you. Eating me seems like the easy solution. But that’s a mistake.”

“And why would that be?” The Mer’s nostrils flared, his lips pulling back into a sneer.

“Because - well, that would be _boring_ , wouldn’t it?” John smiled wryly, “It would be an ending. You like the challenge of - of the hunt, as it were. You’re bored. You said that this was an unusual night for you, too, that I was interesting - why have it end here?”

The Mer’s tail flicked beneath the waves, and his eyes narrowed, “You’re proposing that I leave you alive so that we may continue our...association.”

“You’re curious about me,” John said, “And I’m curious about you. I don’t see why my untimely demise should break what could be a...mutually satisfactory liaison.”

The Mer watched John, pensive and silent.

“If nothing else, James, I admit you are quite singular to your kind,” he replied finally, “And I admire your tenacity. However, if I may point out several things?”

John waved a hand, signaling the Mer to continue.

“I _did_ intend to make you my meal,” the Mer said, and the deep tone of it made John’s blood run cool with adrenaline, “Agreeing to your proposal will leave me without one. I can overlook this concern; I do not eat for days on end, but if we strike an accord I will continue to hunt, though not from your vessel. Do not ask me to stop. However, what I cannot overlook is the fact that your bargain is, by nature, unequal.”

“Unequal?” John’s brow furrowed, “In what way?”

The Mer smirked, “In exchange for not taking you as a meal, you are offering yourself as a conversation partner. The idea has merit, but surely several conversations are not worth a human life.”

John considered this. “It depends upon the conversation, I suppose.”

“Indeed,” the Mer chuckled dryly, “Still, it would be difficult to arrange. We would have to meet in secret, yet out in the open in the middle of the night. Discovery would be perilous for either of us. All you are offering is your word that you will speak with me, and not reveal me or my kind to other humans. Surely the risk and reward is skewed in your favor.”

“What would even the stakes, then?” John asked.

The Mer frowned in thought, “Collateral, of some kind. Something you can give me to keep in my possession that you would wish to see returned safely.”

“Okay,” John said. He tipped his head to the side, acknowledging the fairness of this point.

“Perhaps what you have in your pocket.”

John stiffened. He’d been about to reach into his pocket and stroke the lacquered wood of the compass again, his talisman of good luck. He never went anywhere without it, now.

He thought of denying its existence, but the Mer clearly had excellent sight and had spotted its form in his trouser pocket when he swam closer. Pressing his eyes closed briefly, John pulled the compass from his pocket and held it in his outstretched palm.

“This?”

“Yes,” the Mer’s eyes were bright in his upturned face. “What is it?”

The earnest curiosity of the question almost made John bark out a laugh, “What is it? It’s a compass. Surely you’ve seen one before.”

“None quite like that,” the Mer said, “What is it for?”

“It - it tells direction,” John flipped the wooden lid open, revealing the gently turning disk inside, inscribed with neat black arrows and letters, “To guide men and ships. It will always point north.”

The Mer shook his head, the dark curls ruffling softly, “You are telling a half-truth. You do not keep this _compass_ just for that purpose. What else is it _for_?”

John’s grip tightened on the compass,and he snapped it shut with a sharp click.

“Ah,” the Mer said, “ _Sentiment_.”

“Will it do, then?” John replied sharply, and more loudly than he had intended.

“If that is what you wish to risk for yourself, it is acceptable to me. Sentimental value makes it a bigger gamble on your part, which evens our odds nicely.”

“It’s also a risk for me to keep meeting you,” John said, “You could sing me off the side of the ship if you really wanted to. If I grew to bore you.”

“You will have to hope that you do not,” the Mer looked delighted at the thought, “And yet you would continue to meet me under the cover of night? What a dangerous risk to undertake.”

“Maybe I like the risk,” John murmured huskily. The Mer smirked, pleased.

“You _are_ fascinating,” he said, heaving away from the rock and sliding back into the deeper water, “Quite the puzzle. I do not think I will regret letting you live, James.”

“I hope not,” John called softly, watching the Mer sink until only his pearly eyes and the dark curls on his head were visible above the waves. He ran his thumb over the carved wood, feeling the softness that came from near constant handling of the compass. “If I give you my collateral, can you give me something as collateral in return?”

“That is fair,” the Mer nodded, bobbing above the surface and swimming closer, so he was nearly right below John.

John bent at the knee, carefully keeping the weight off his stiff leg. The Mer looked up at him, absorbing the subtleties of the movement. John dropped the compass in its wooden housing, and the Mer caught it before it splashed. He craned his neck upward again, expectantly.

“Your name,” John said quietly, “Your true name.”

A smile bloomed on the Mer’s face, one different from all its brothers that had come before. The Mer looked truly elated, grinning widely but without a trace of malice, and it made him look even more beautiful.

“Oh, _clever_ ,” the Mer breathed, “Clever indeed. No human has yet to hear my name; you do not really need to call us by name to bring us to a ship.”

John raised his eyebrows. “No?”

“No, but the next time we meet you will have the pleasure of doing so,” he smiled, “My true name is Sherlock.”

“Sherlock,” John repeated, trying the feel of the name in his mouth, “When will we meet again?”

“The night of the quarter-moon,” Sherlock said, and dipped his chin in an acknowledging nod. “Goodnight, James.”

As he sank beneath the waves, Sherlock’s pale eyes stayed locked on John. With a flicker of silvery movement beneath the water, he disappeared into the sea.

John stared for a few moments longer at the dark surface, the ripples smoothing out. It was already like the Mer had never been there. He shook his head, as if to clear out cobwebs that had accumulated there. The threads of the Mer’s magic were unwinding around him; he hadn’t used the song, and he didn’t have John’s true name, but they had started to cling to him nonetheless. John resisted the urge to brush out his shirt and trousers.

The candle stuttered and finally died as he stood there, contemplating. Darkness swallowed up the ship, and John made his way to the ladder by starshine. It was slow going, feeling his way back to his cabin in the dark. He collapsed into bed when he reached his small room. It felt less cramped and claustrophobic now, if only because his mind was brimming with what he’d seen and heard, shutting out all thought of his recent insomnia.

But for all that filled his head he did sleep, finally, rocked gently by the _Zephyr_ on that fifth moonless night.

 

 

 

•

****

As John slept, he dreamt.

He dreamt of blood splashed onto sand, growing dark as it seeped into the perfect white grains in a wide, red stain.

He dreamt of bright, golden light filtering down through the water, and looking up at the mercurial colors above the waves.

He dreamt of a melody, aching and haunting though it had no words. It was deep and gentle, and pulled him further down, down into his slumber.

He didn’t remember the dreams when the sun rose.

 

 


	2. Chapter 2

**Summary for the Chapter:**

> At the heart of it all: how much of the stories were true?

**Notes for the Chapter:**

> Thank you very much for all of your kind comments! I am very glad to hear that you've been enjoying it so far! As a belated birthday gift, the lovely [Chelsea](http://tea-is-hot.tumblr.com/) drew [Mer!lock fanart](http://tea-is-hot.tumblr.com/post/48569433769/happy-very-late-birthday-venvephe-a-sort-of) based on the first chapter of 'and the sea so deep' - it is amazing and beautiful, and perfectly depicting the first encounter between John and Sherlock.

Days on board the _Zephyr_ were nothing like the nights. Where nights were mostly still, quiet and serene, the days were busy and loud and fraught with ever-growing lists of tasks to complete and people to speak to. John was often awake with the first peek of the sun over the wet, blue horizon, watching the stars fade and the sky lighten as the world awoke. Mornings had been easier since he’d started to sleep better - since he’d met - well. Since. The skies had been clear, or dotted with cotton-like clouds; the vibrant blue and white lightened John’s heart. Like a vanishing shoreline, the past seemed to be receding from him, further and further away. His dreams were filled with something different, now. His wakeful moments, too, found his thoughts moving in new orbits.

John had two nights before the quarter-moon, two nights to figure out how he was going to arrange his agreed-upon meeting with the Mer. The question was, undoubtedly, _how_ : John already knew that he wanted to see Sherlock again.

The problem of seeing Sherlock was multi-faceted. John hadn’t asked where they would meet; he assumed that, once again, the Mer would approach him when he was on-deck, in the middle of the night. He hadn’t thought to ask what would happen if the _Zephyr_ made berth at a port, or if the night was stormy, or if any of the thousand other circumstances and mishaps that could befall a frigate in the Caribbean came to pass.

It plagued him, crowding out his other thoughts as he went about his day-to-day duties aboard this ship.

His mind had begun to wander to thoughts about the Mer himself, too. He lay awake in his cabin as the sun finished setting, the light cast on the ceiling blending from gold to orange to pink-red, his thoughts swirling with questions he wanted to ask the Mer when he saw him next. How many of them were there? Did the Song come to them on instinct, or did they learn it, passed down from generation to generation? Did they all share the same appearance - with the stunning pale features and thick, dark hair as Sherlock had, as supposedly Aeserena had?

And, at the heart of it all: how much of the stories were true?

 

 

 

•

****

As happenstance would have it, the hectic life aboard the _Zephyr_ worked in John’s favor.

They were still two days out of port, out where the sea floor dove deep into canyons and the water was dark, dark blue. The weather had held sure for them, to Lestrade’s pleasant surprise and Anderson’s dismay, as the latter had predicted a storm when they’d left the Dutch Indies now almost a week past. The Captain was pleased, though, as was John; good weather meant routine sailing, and routine sailing meant no surprises.

This hadn’t been true for the ship doctor, but the tedium of sailing in good weather meant that no one had taken ill, and John much prefered his fellow crewmates whole and unharmed.

Their luck held true until night fell.

John was laying in his bunk, awake deep into the night for the first time in days, listening to the rumbling groans of the ship as the breeze turned to wind, and then the wind to gusts and the gusts to gales. Tension knotted uncomfortably in his chest; storms at night were never good, between the rolling and pitching of the ship and the decreased visibility. It was too easy to lose a man overboard.

His mind fled immediately to the myths, but he shook his head to clear it. No, it had been days since he had seen Sherlock, and those days had been bright and sunny and fresh with nothing more than a steady breeze. There was no evidence, thus far, that the Mer truly did bring storms with them. It was surely a coincidence that the weather was turning on them now.

A loud thunk resonated through his cabin, followed by muffled, wind-bitten shouts that John couldn’t quite make out. The urgency of the tones carried, however, and John’s feet were on the floor before he had made a conscious decision. He didn’t bother slipping on his shoes, only pulled a shirt over his head on his way out the door and up the rain-slicked stairs to the main deck.

John had to squint against the sudden torrent of rain and brackish seawater. The decks were soaked and shining, partially engulfed by greedy waves each time the _Zephyr_ pitched and rolled. Foamy residue from the angry, churning water clung to the wood only to be washed away and rearranged by the next deluge. Bringing one hand up to wipe the water away from his face, John braced himself and scanned the decks. There, port on the mid-deck, splayed on what must be the planks right above his cabin: Murray was soaked through and clutching at his right hand, Anderson at his side amidst the chaos on deck. Murray’s arm and forehead were streaked with blood, his white shirt stained a muddy, diluted pink. He was trembling but speaking, though John couldn’t hear him; it was Anderson’s voice that had carried on the wind down through his open porthole window. The rest of the crew was too occupied in keeping control of the ship in the vicious storm to stop and aid them.

Setting his jaw, John strode purposefully across the slick deck, clutching at a railing until he reached his injured crewmate. He dropped to his knees, and put a steadying hand on Murray's shoulder. Anderson nodded at him in acknowledgement, knowing he wouldn't be heard over the howling of the wind and the booming, thunder-like snapping of the taut, waterlogged sails. The ship heaved and groaned as it broached the crest of another wave, as if adding its own cries to the cacophony of the storm. John and Anderson leaned with the movement, keeping their balance until the ship settled back towards horizontal.

Murray's palm had been ripped open in a ragged line, the skin surrounding the wound was roughened and red. The path of the damaged skin continued in both directions, snaking around to his abraded knuckles on one end, and down his forearm, where blood was beading within the abrasions at the other. The angry red marks looked snake-like, coiled around Murray’s arm in stark contrast to the unnaturally pale cast of his skin.

Within moments of inspecting the wound, John pulled his now-soaked shirt over his head and wrapped it around Murray’s hand, not bothering to try and wring any water out of it first. It would do for the moment - at least until they had gotten Murray off the slick and lurching deck.

John shouted “Inside!” as loud as he could, jerking his chin sharply towards the below-deck door to convey his meaning over the wind. Between the roaring of the sea, the rain and wind, the flapping and rattling of the ship’s rigging around them, John wasn’t sure Anderson had heard him. He’d gotten the idea well enough, though, slipping one arm around Murray’s shoulders and helping him to sit upright. Between the two of them, John and Anderson half-helped, half-carried Murray across the main deck and down to the crew’s quarters and out of the weather.

“Here,” John said when they had reached the crew quarters, slowly lowering Murray onto the empty bunk nearest the hazy yellow lantern. “Keep him still, I’ll fetch my kit.” Anderson nodded absently, concentrating on pressing John’s shirt to the gash on Murray’s hand. The blood flow was slowing, but the wound continued to ooze sluggishly. Murray groaned, eyes screwed up in pain.

It took John only a few moments to bang back into his cabin and grab the kit from the small table. The color in Murray’s cheeks had begun to return when he approached them again, though he’d started shivering more in the interim.

“Are you needed on-deck?” John asked Anderson, sitting on the other side of the rumpled cot without preamble.

“I can assist you in patching him up before I go back up,” the man replied, adjusting his grip on the makeshift wrap. John’s shirt probably wasn’t going to be salvageable after this. “Captain’s going to want to know what happened.”

“What _did_ happen?”

“I didn’t see it, only heard it,” Anderson replied, leaning back as John slid forward and gently pulled his bloodied shirt away from Murray’s hand, “Rope, from the looks of it, though. He was on rigging.”

“Something snapped,” Murray said in a hoarse voice, pausing to cough wetly. John put a hand to his shoulder. “Pulled the rope right through my hands. Thought it would fling me into the ocean.”

John shook his head, “Hold still. It’s going to sting while I patch you up, but we’ll see to that cut first and then clean up the rope burns, yeah?”

They went quiet as John worked, hands steady as he expertly cleaned the gash on Murray’s palm and threaded the thin needle with dark thread. It went as easy as could be expected; Murray bit at his other hand to stifle his grunts as John worked the needle swiftly, stitching the ragged flesh back together. For his part, Anderson was a competent assistant, passing anything John requested in his quiet, firm tone. The storm still raged above them, shouts of the crew muffled and the skeleton of the ship continuing to creak and sigh.

“There,” John finally pulled back, wiping away the streaks of blood that had mostly dried on Murray’s forearm, “I’ll see to it again in the morning, but it should be good for now. It looks pretty clean, all things considered.”

“Seawater stung like a bitch,” Murray heaved a sigh, “Thanks, Doc. You’re a godsend.”

“Indeed,” Anderson quirked a brow and stood, rolling his shoulders. For a moment, his gaze lingered on John’s bare chest, down and to the left, though his eyes flicked quickly back up. John stiffened. With his shirt off, the warped flesh of his scar was visible, a pink starburst of skin on his shoulder.

“I’ll alert the Captain. He won’t be pleased, but we can manage in the storm even with a man down, I should think,” Anderson said.

“He’ll need a few more day’s rest, besides,” John frowned, “He’s had the wind knocked out of him and that should be all right after a good night of sleep, but his hand needs well near a week before he should be handling rope again.”

Anderson paused, “What are you on, Murray?”

Murray groaned again, “Nights, fuck. Cap needs me on the rigging at night. Donnie can’t see as well in the dark as I can, doesn’t know the ropes by feel yet.”

There was no way Murray was going to be in any shape to handle the night shift with his hand like that; from Anderson’s grimace, the second mate knew that as well.

“I’ll cover for him while he’s healing,” John said, nodding at Anderson, “Tell Lestrade. He should be fine with it.”

Anderson glanced skeptically from John’s left shoulder to his knee, and then up to his eyes again. Something shifted in his expression, though, at the determination written on John’s face. “Very well, Doc,” he said, turning away already to head back up to the stormy main deck, “You’re...more than I expected, yet again.”

The backhanded compliment made John wrinkle his nose when Anderson turned away, but he just sighed and turned back to Murray.

“He’s kinda right, you know,” Murray said, wiping his sweaty hair off his forehead with his uninjured hand, “Didn’t know what to make of you at first, doctor with a limp coming onto a privateer? One that wasn’t born a sailor? None of us knew what to do with you.”

“Didn’t know what I was doing with myself, if I’m perfectly honest,” John shrugged, a wry smile twisting on his lips as he perched on the edge of the cot to pack up his medical kit.

“But hey, Doc,” Murray clasped his elbow, stilling John’s movements, “I’m glad you’re here. And your leg’s been getting better, lately, some of us have noticed.”

John paused. He himself hadn’t noticed it. The memories trickled through his mind fluidly - the way he’d raced up the stairs and across the deck to Murray, carried him down to the crew quarters, kneeled by his side without any complaint from his leg to hamper his movements. And in the few days before, too: he’d sidestepped nimbly before a sliding, snakelike rope made him trip, darted around Stamford who couldn’t see over the large cask he was carrying.

He cracked a weak smile, reeling from the revelation. “I wasn’t sure you noticed me at all,” he said, feigning humor he didn’t quite feel.

“Bollocks,” Murray chuckled, which ended on a wheeze, “Won us over with your stories. Provided you keep us in ship-shape, we’ll all keep our eyes out for you.”

“Thanks, Murray,” John did smile then, patting the sailor’s shoulder as he stood. “Make my job easy and don’t fuss with those bandages. I’ll check on them in the morning.”

By the time John collapsed into bed the storm had started to abate, the winds ceasing to howl as ferociously and the seas calming. The patter of rain was more audible than anything else as the ship settled, the temper of the storm passing and leaving behind the softening rain they’d have to wait out.

The sound of the rain - rhythmic, steady - was a balm to John’s adrenaline-hyped body and mind, and he stripped and dried himself with the sense of warm satisfaction that comes with a job well done. His skin and hair was tacky from the wash of brine that had dried there, but he resolved to deal with it later, when the sun had risen. His leg was twitching with a dull ache, but that was all right; it had been markedly better lately, and it only protested a little as he climbed into his bed. John smiled to himself, wiggling his toes. It was a basic comfort - a warm bed after a night of wet weather - and he knew he wouldn’t have a problem finding sleep.

He was right.

 

 

 

**•**

The ship was still and silent.

The pale light of the quarter-moon washed out the colors that were, in the daylight, so rich aboard the _Zephyr_ : the red-brown of weathered mahogany and oak, the navy and forest-green paint, the inlaid brass and copper and iron and steel. Everything was bathed in the milky light, which dampened the vividness of the ship. The moon bled the colors dry. Only in the yellow circle of John’s lantern did the ship’s colors echo the brightness they held in the sun.

John had been lucky. When Lestrade had heard that John would be taking Murray's night shift, he'd decided to lay anchor. John wasn't a proper sailor, not really; he'd taken well to life aboard the _Zephyr_ , but the only true training to his name was that of a doctor.

"And God help me, I'd like to keep it that way," Lestrade had nodded, though he'd kept his eyes on the distant horizon in front of them as he adjusted the angle of the wheel. Night had already begun to fall, then, the sky streaked with orange and pink.

"There are few trained doctors on privateer ships, as you can imagine," the Captain had continued, "And as long as you're amenable, I'd like to keep you. Murray's hand is looking well - you did some good work there, by the way." John had smiled and accepted the compliment, stomach fluttering at the news that he would, once again, be alone on the decks of the _Zephyr_ for the next three nights - the first of which was the night of the quarter moon.

Now, quiet and dark, it was just a matter of waiting.

John’s back had started to get a little stiff in the past hour - he couldn’t have been on-deck more than thirty minutes before his encounter with Sherlock, the last time - and tonight he’d started his watch before moonrise. The quarter-moon had risen, faithfully, a perfect white half like a china cup spilling stars across the darkened sky. A faint breeze stirred the water and the fabric of the sails, making gentle ripples on the surfaces of both.

John shivered, rubbing a hand up and down his arm to soothe the goosebumps that had started to form. The air was cooler than it had been when the sun set, hours past.

The bones in his knee popped and groaned when he hoisted himself upright, resolving to take a lap around the ship before settling down again to watch and wait. It had been such great luck, that he managed to secure this time on the deck that they could meet, alone and uninterrupted; surely Sherlock would remember and find him, wouldn’t he? How large were mermaids’ territories, anyways?

His mind blossoming with questions, John approached the bow, stepping carefully over the dark, snake-like coils of rope piled at base of the foremast and shrouds. The metal links of the anchor-chain were cold against his toes as he knocked into them, accidentally, his lantern casting a gold glow on the strange stillness of the sleeping ship. It was a strange contrast, the enveloping silence and stillness of the unmanned _Zephyr_ at night; John felt a little bit like an island unto himself in the vast, stretching darkness.

The bowsprit angled upwards, towards the star-studded sky, but it was level enough where it met the bow of the ship for John to rest his lantern there without it sliding off. John peered over the edge to the water below, leaning his elbows upon the cool railing. The moon’s half-light masked more of the stars tonight, the wide belt of the galaxy more of a hazy blue-purple than the dense pinpoints of light it had been in the perfect darkness almost a week before. The rippling water disturbed the reflection he looked down, growing more and more unsure. They had, indeed, agreed upon the quarter-moon and not the half?

“Sherlock,” John sighed, letting his tongue wrap around the name. He’d never heard another like it; sailors had practical names for themselves. They were often called by their last names, or easy nicknames - like Doc, as he’d been affectionately christened by the crew - nothing like _Sherlock_. Sherlock’s name was the likes of which were found in legends and constellations, painted delicately across the bows of ships. Like _Zephyr_ , and Aeserena.

Sherlock, he thought again, the name flooding the surface of his mind.

“James,” a deep voice answered from below, and John started in surprise.

The Mer’s chuckles echoed as he looked up at John, amused that he had snapped him out of his reverie. He had appeared in the water as naturally as if he were a nymph born from the gentle ripples; he was unearthly, with the soft moonlight catching on his pale skin and dark hair. The moon’s reflection, cast into shards with the movement of the water’s surface, danced about him.

“Sherlock,” John exhaled, his heart picking up its pace deep in his chest, “I didn’t think you’d- you, um, managed to surprise me, yet again.”

“You called to me, James,” Sherlock raised his eyebrows, smirk still in place. A shudder passed along John’s skin; yes, he had called the Mer’s name, and he had appeared at the sound of it on John’s lips. Sherlock had told him it would work, but he hadn’t quite believed it would be true.

They spent a quiet moment watching each other; Sherlock’s face settled into a familiar expression of bright curiosity, and John knew he must look a fool for the way he was staring unabashedly at the pale, shining form of the Mer.

Sherlock held his wrist out of the water. There, on a strand of twisted leather laces, was John’s compass. He had managed to thread the lace through the hinge to keep it secured on the strand - for safekeeping and transport, John realized -  and it now made for a strange, clunky wooden locket.

“Your collateral,” Sherlock said, and John nodded, clearing his throat to find his voice.

“Yes, thank you,” John said. The silence swallowed his words quickly, and they were wrapped in the quiet murmur of the waves against the bow of the ship for a few moments longer as they eyed each other.

“Well, come on, then,” Sherlock sighed as if put-upon, craning his neck to John’s right and then diving smoothly beneath the surface. John watched his silvery form, distorted from the gentle ripples, as he swam along the starboard length of the ship, towards the quarter-deck. He picked up his lantern and half-jogged to keep up, though Sherlock had already broken the surface and was waiting for him by the time he set it down again. John settled himself on the deck proper this time, centered neatly in the gap of the railing. He crossed his legs beneath him and kept the lantern close by his side, so that its light pooled downwards to illuminate the Mer’s face. Sherlock was backlit by the moon, and the pearly light turned every glistening drop of water that dripped from his hair and slid down his shoulders into a prism, a diamond. He was mesmerizing.

The compass bobbed in the water next to Sherlock as he leaned back; strong, lazy pumps of his tail kept him at the surface of the water as he stretched out, his eyes glittering. Of course Sherlock knew that he admired his form, John realized; he couldn’t take his eyes off the Mer if he tried, just like the first time. It was equal parts awe and medical fascination, he told himself.

“Are you well?” John called to him as he shifted, trying to sit comfortably on the worn planks of the deck. Sherlock tipped his head to the side.

“Yes,” he replied, after a moment’s hesitation. His pale eyes were narrowed, transfixed on John, but a smirk was pulling at the corner of his mouth.. “You realize that you are putting yourself in danger, at great personal risk, to ask questions of me - and the first thing you inquire about is my well-being?”

John chuckled, grinning both the truth of the Mer’s statement and his own deep-seated English mannerisms. “I didn’t think it kind to start off our conversation with a prying question. Are Mer only polite when they are hungry?”

“No better of a question than the first,” Sherlock snorted, and didn’t answer him. John’s smile broadened.

John would bet that aside from their encounter before, Sherlock had probably never had a conversation with a human that didn’t feature the dark, seductive thread of magic or Sherlock’s own variation on the Song.

There was so much about the Mer that he wanted to know; he wanted to pick apart the stories and fill in the holes and half-truths with what he learned from Sherlock. He wanted to spend his moonlit hours speaking with this amazing, beautiful creature; he wanted the crick in his neck and the night of ocean dreams their encounter would invariably bring.

Sherlock blinked up at him, expectant.

“Do you breathe above-water?” John asked, the question out of his mouth before he could stop it. Sherlock snorted and he felt his face heat, but Sherlock answered him nonetheless.

“Already with the biology questions,” he arched his neck, baring one side to more fully expose the horizontal ridges to the moon’s light. “You can see I have gills; breathing underwater is innate to Mer. But we have human-” he tapped the side of his nose and gestured vaguely at his torso “-breathing as well.”

“Lungs,” John supplied the term for him, “It makes sense, I suppose. You need to have vocal chords to make human sounds, which is part of your...hunting.” John trailed off, jaw tightening fractionally.

“Indeed,” Sherlock raised an eyebrow; his tone remained the same, formal and cool, but his eyes were appraising. John found that he liked being able to surprise him; he could only hope that he remained an object of fascination for Sherlock, as Sherlock was for him. The balance between them was still too delicate and new. John didn’t fancy being lured into the water tonight or any night soon.

“You have a navel, too,” John observed, waving a hand at the pale skin of Sherlock’s midsection. He was all whipcord muscle and planes of flat, pale skin; even there, where a trail of dark hair would travel down, down on a human, Sherlock’s skin was pristine and smooth to where it seamlessly melted into scales. Something stirred in his gut as Sherlock pinned him with his lamp-like gaze.

“You’re born, then? Natally?” John continued, clearing his throat to shake the roughness in his voice.

“Obvious,” Sherlock intoned.

John frowned, “Not to me, it isn’t. Don’t fish usually lay eggs?”

“Not all fish,” he replied, rolling his eyes as if this fact were also obvious. John, not a native to the coasts or the seafaring life, didn’t know any better. “And you should know, James - the Mer are _something else entirely_.”

Sherlock’s voice dipped deeper with those words, and a tense silence settled over the ship in their wake. John let the sighs of the ship wash over him as his thoughts swirled, muddled, in his mind. He toyed with the fraying threads at the bottom hem of the lightweight pants he’d worn to combat the heady warmth of the night, feeling even warmer under the weight of Sherlock’s gaze.

“I am not surprised,” Sherlock finally broke the silence, “That you chose to ask questions about our physicality, first. You are a healer; you would be most curious about that.”

“Doctor,” John corrected, “But, yes, I admit I’m rather intrigued about Mer and - well. You’re straight out of fantasy - and yet clearly - you’re _real_.”

Sherlock’s lips tilted in a slow, smug smile; his tail moved languidly in the water, gently stirring the surface.

“You don’t mind, though?”

“Mind?” Sherlock blinked up at him.

“Answering questions about your biology,” John said.

“James,” he sighed, “Believe me when I tell you that if there is a question I do not wish to answer, I will not answer it.”

John's brain itched with how much he wanted to know, but he was hesitant to go down some of the paths that his thoughts supplied. The Mer were dangerous, however beautiful, and John was reluctant to approach any subject that might touch on the delicate line of predator and prey that he and Sherlock were flirting with.

“Sherlock,” John began with a wry smile, giving up in his efforts to find an eloquent question and getting at the heart of his bafflement, “I’m still having trouble believing that the Mer are real.”

“The evidence is right before your eyes,” Sherlock lifted his eyebrows, “Ask.”

At the word - the command - John felt his pulse jump in his neck, and was glad that the darkness masked what was undoubtedly a warm flush across his cheeks. Sherlock’s tenor tugged at something in his mind, deep and reaching.

“Are you warm-blooded, then? If you have human lungs and live birth,” John said, before he lost the nerve to speak.

“Yes, we are warm. The only hair we have is here,” Sherlock gestured to the damp, glistening curls at the top of his head, “But the temperature is never a problem.”

“You must not go far beyond the Caribbean,” John said, thinking of the bracing, chilly waters of the Atlantic. Even in the summer, the oceans never approached the mild temperatures of the Caribbean Sea.

“Our range is limited, yes,” the Mer acknowledged, “But it is as much a matter of preference as it is our nature. We go where the hunting is good. These waters happen to be rife with activity.”

“That would explain why all the stories of the Mer come from around here,” he mused.

“As you have mentioned,” Sherlock murmured, “What do these tales say of us, exactly?”

It was a subject John had grown rather familiar with, increasingly so as of late. He’d revisited his memories of muttered tales, tucked in the back of dim-lit taverns, or told to a captive audience that sipped their ales and listened with rapt attention. The stories were well-worn and often retold, though they paled in comparison to the living vision lit by the cool spring moonlight.

“Some of it you must know,” John said, “Pale skin, dark hair, enrapturing eyes - and voice. The torso of a human woman and the tail of a fish, a beautiful but dangerous creature that sings foolish men to their deaths.”

Sherlock snorted, eyes glinting. “Poetic and dull. Mostly true, but dull all the same.”

“Dull?” John blinked, “They’re not dull to us. Poetic, I’ll grant you.”

“Idealized, most certainly,” Sherlock continued, “And stripped of the harsher details to make it more palatable.” His mouth twisted into a sneer, and his movements beneath the water were quick and sharp, tail flicking back and forth in visible agitation.

“That’s part of the idea of a story, Sherlock,” John said, “It’s based on truth, or what humans know of the truth about the Mer. I can’t imagine there are many who have lived to tell the tale in its entirety.”

Sherlock looked at him oddly for a moment: a long, measuring glance that John could now tell meant that Sherlock was reassessing him. He’d said something that piqued Sherlock’s curiosity.

“Indeed not,” he finally replied. “And yet here you are, seeking out the truth, no matter the danger it poses to you.”

“I thought we established that I liked the danger,” John smirked, nudging the nearby lantern with his foot so that it scooted closer to the edge of the ship, casting more light on form below, “And I know you do, too.”

“Oh?” Sherlock was grinning now, though the hint of teeth that gleamed in the moon’s milky light were sharp, even from the distance. “Is that what you have gathered about me, from our brief acquaintance?”

“You do,” John affirmed, “You said so yourself, that it’s dangerous for us to be meeting each other. It must go both ways. For me, it’s simple; I’m prey, and there’s always a chance that you’re going to lure me into the water to eat me. You didn’t mention why it is dangerous for you, though.”

The Mer didn’t reply but his eyes were bright, challenging.

“What _is_ said of the Mer, in the stories, is taken as just that - fiction. It would be dangerous for you to be real, wouldn’t it? The Mer would be hunted,” John’s fists tightened in his lap, “Something exotic for humans to hunt and kill and display. More spoils from the sea.”

“We are rather more intelligent than fish, thank you,” the Mer rolled his eyes. He didn’t deny John’s theorizing.

“But exposing yourself to a human without taking them...” John frowned, “That’s putting yourself at quite a risk. Not just yourself, but all Mer. Leaving that kind of evidence...well, the stories start to appear.”

“All stories are based on truth,” Sherlock murmured. The gentle water around him stirred, and John heard the sails shift with the breeze that brushed against his face. The moonlight caught on the ripples and soft crests that marred the dark surface. Sherlock’s pearly eyes bored into him.

John couldn’t tell if Sherlock was agreeing, or repeating John’s own words back to him. He didn’t get the chance to ask.

“We have stories about you, too.”

“About us?” John raised his eyebrows, “Humans?”

“Yes,” Sherlock nodded, “I am curious, as I have told you before. Perhaps the risk, to me, is worth the reward.”

“Perhaps,” John narrowed his eyes, “But is it?”

“One does not need to have only one motivation for an action,” the Mer’s smile pulled into a smirk, and he leaned back in the water, floating effortlessly on the surface as he surveyed John’s expression.

John licked his salt-chapped lips as his eyes followed the smooth lines of Sherlock's form, the moonlight catching on his scales like polished pieces of silver. He knew it was a cruel trick of biology, the delicate balance of predator and prey that created such dangerous beauty. Painted frogs warned predators of their poison; peacocks displayed their colorful, fanned plumes to attract their mates. Mermaids, from his observation and Sherlock's explanations, seemed to fall somewhere in the middle.

They were more than beautiful; they were fantastic. The meeting point where fantasy touched reality, the blurred edge where the sea and sky met. Even with Sherlock in the gentle waves not twenty feet from where he sat, John felt awestruck by his existence, and the form that the myriad stories truly took. But they were dangerous. There was a glint to Sherlock's eyes as he watched John. It made the fine, fair hair on his arms and he nape of his neck stand on end. The moments of the silence they shared weren't quite comfortable. As much as they enjoyed each other's presence - if even that much could be said, this far into their tentative relationship - the underlying current of tension that ran beneath their quiet pauses made John's hear thrum a little bit faster. Pinned under Sherlock’s pale gaze, John felt both trapped and alive.

“Here,” Sherlock pulled at the leather laces at his wrist, deftly untying the knots with one hand. The compass bobbed free for a moment; he scooped it out of the water and lobbed it, gently, up to the ship. John watched the muscles in his arm shift in the throw - the Mer was mesmerizing in every way he moved - and he managed to shake himself into moving in time to catch his compass before it collided with the deck. It made a satisfying smack in his palm, the wood still soaked and saturated from the water, and John turned it over in his hands.

“My compass?”

“Returned collateral,” Sherlock called up to him; he didn’t bother to disguise the obvious disdain in his tone at having to explain himself.

John looked up, eyes widened in surprise. “Why?”

“It is no longer adequate collateral,” the Mer smirked, “We should increase the stakes, James.”

John’s mouth went dry. He leaned forward, swaying towards the figure bathed in moonlight. "To what?" he murmured, “What do you want from me?”

“Your word,” Sherlock’s voice resonated deep in John’s chest, even from the distance between them.

“My word?”

“And nothing else,” the Mer nodded, his smile now small and secretive, “On the night of the full moon.”

John plotted out the calendar in his head, thinking back to the ship’s itinerary he’d gone over with Lestrade. “Eight days from now? We’ll be in port by then-”

“And you will find a way to come to me, if you wish to continue our liaison,” Sherlock’s eyes were sharp and bright, lit with the reflection of the moon on the water. He dipped further into the sea, allowing himself to sink deeper before a sinuous push of his tail kept him at the surface. His skin shone wet with water and moonlight.

Clearing his throat, John held Sherlock’s gaze, “The full moon, then,” he replied softly.

For a brief moment, the Mer’s smile was wry and amused, his soft lips quirked at something he saw in John’s eyes. But just as quickly, it had vanished, and with a parting “Goodnight, James,” in his deep baritone, Sherlock sank beneath the waves and darted out of sight, a glimmer of silver that was quickly lost in the reflection of the silent moon.

John spent the rest of his night shift with his flickering lantern and his thoughts, caught between the golden candlelight and the soft rays of the moon.

****

 

  
•

 

The horizon was more dusky pink than orange when John finally fell back onto his bed, the first rays of the sun casting gold-orange shapes on his ceiling. He stripped out of his shirt and cotton trousers efficiently; if he was lucky, he could get in a few hours’ sleep before checking on Murray mid-morning.

A growing wet stain was forming on his sheets where the compass sat, upside-down where it had fallen when John had sat down. It was still damp and cool to the touch when John cradled it in his hand, smooth wood and worn weather laces. He turned it over in his hands once, twice, before placing it on his bedside table next to the snuffed lantern. John leaned back, settling into bed, feeling both comforted by the returned presence of  his compass and exhilarated by his second encounter with the Mer. John hadn’t known what to expect; Sherlock had surprised and enticed him, once again. Couched safely in his room once again, John didn’t shy from the blossoming heat in his chest at the thought of Sherlock.

There was something feral about him, contained below the surface. It was easy to overlook, with the Mer's aristocratic turns of phrase and acerbic wit, and the extensive albeit patchwork knowledge of the human world he possessed. It didn't make him any less of a predator.

Because that's what the Mer were. Sherlock couched the fact with charm, with undeniable grace, with cleverness. He was a vision; pale skin and dark curls all but made for catching the moonlight, and eyes that, like opals, caught and held an array of blue-green-gray-purple-white. But the firm muscles of his arm were for grabbing and holding, and his shining, powerful tail was for diving deep beneath the waves, and his voice....his voice...

Something was building in John's mind. Layer by thin, gauzelike layer, it formed like a pearl and settled in his thoughts, consuming more and more space. But what it was exactly he couldn't put his finger on.

****

 

•

****

Salt was drying in delicate lacy patterns on the surface of the compass when John awoke, bone-white against the dark red mahogany. The sunlight that spilled in from the windows was cool and bright; mid-morning, then, and time for John to make his rounds.

His dreams had been vague and soft and rolling, indeterminate in shape, ever-shifting foam on the cusp of each wave as it lapped at the shore. Threads of sleep still clung to him, comfortably warm in a tangle in his sheets; John sighed, pushing himself upright and setting his feet on the cool floor, blinking himself awake.

John reached for the compass. It was a pleasant weight in his palm, still damp around the metal of the hinge and clasp, but it opened without complaint. He hadn’t checked, the night before, to see if any water had gotten trapped inside.

True to his word, Sherlock had kept the compass in pristine condition under his care. The delicately etched windrose was just as John remembered it: its sixteen points carved and painted with a patient hand, cardinal directions a deep blue and the bold N for North a proud crimson. As he watched, the brass needle swayed and swiveled, rocking with the ship until it reached their bearing.

But then - it spun away.

Away from west, stopping as abruptly as it had started. Clockwise, to east; two full rotations to south-by-southwest; north again, but only for a fragment of a moment before it was spinning, twitching, pointing this way and that. John watched, enraptured, as the needle flew and spun, never resting.

The compass no longer pointed north.


	3. Chapter 3

**Summary for the Chapter:**

> For all that John had seen of Sherlock on the previous nights, under the lantern-light and the muted rays of the moon, the Mer was so much more.

**Notes for the Chapter:**

> Firstly I want to apologize for the lateness of this chapter - a lot has happened between the last update and now! I really can't thank you enough for your continued interest and support of this story, if you've stayed subscribed and have been writing comments on each chapter. It means the world to me. 
> 
> Part of my radio silence has been a result of NaNoWriMo, which I successfully completed this November - and I'm proud to say that about 35k of the 50k words I wrote is new material for "and the sea so deep"! These coming months should see many more and frequent updates as I sift and edit what I've written; this story is far from abandoned! I'm very excited with what I've produced and I hope you will be too!
> 
> Finally, thank you so much to my team of cheerleaders and betas - [Ashley](http://guixonlove.tumblr.com/), [Ruth](http://youseebutdontobserve.tumblr.com/), and my lovely [Meg](http://forsciencejohn.tumblr.com/), for being the best friend and reader a girl could have, and especially [ Allison](http://wearitcounts.tumblr.com/), whose comments were invaluable. This story would not exist without their support, encouragement, and feedback. And, of course, for [Michi](http://traumachu.tumblr.com/), without whom I would not still be in the Sherlock fandom or endeavoring to write my own fanfiction at all.
> 
> For fic progress updates and writing snippits, you can find me on tumblr as [venvephe](http://venvephe.tumblr.com/), where I update quite frequently with my current projects.
> 
> Enjoy and Merry Christmas!

 

 

The moon was heavy and full and bright, a white medallion in the star-studded sky that lit up the shoreline as clear as day. The docks that jutted out into the shallow water at the edge of the bay were bathed in the milky light, the gentle ripples of the calm sea forged silver with the moon’s reflection. As soon as John had seen them on the distant shore - far along the crescent of the beach, away from the bustle of the cargo landings and moorings for ships in Port Royal’s dockyard - he had known the rocky shallows and salt-weathered piers would be perfect for meeting Sherlock.

John hadn’t bothered with a lantern when he had seen that the scattered, wispy clouds were slow-moving on the horizon, unlikely to mask the face of the moon in his sojourn away from the _Zephyr._ The stars were muted by the glow of the moon’s face, all but the brightest lost in the deep blue-black of the night sky. It was a perfect night for a quiet walk on the sand, away from the noise and crowd of the tavern, away from the stifling presence of the same people for weeks on end. That was the excuse he’d given his crewmates, at least; they’d believed him on the virtue of his newness to sea life and the yearning he claimed to have for solid land under his feet.

He hadn’t had to wait long - Sherlock had appeared out of the water like a phantom, grinning at him in pleased recognition. He’d shaken the water from his hair and pulled himself onto a sea-smoothed rock, lithe muscles of his arms bunching and flexing, before greeting John with a deep drawl: “James.”

The warm, dark tension coiling in John’s stomach was instant. It was a visceral temptation, to be so close to the Mer, like nothing he had ever felt before: a bone-deep ache, a delicious tension, an itch that was just out of reach.

For all that John had seen of Sherlock on the previous nights, under the lantern-light and the muted rays of the moon, the Mer was so much more. Within two arms’ distance he was beautiful and breathing and _alive_ , not just a dreamlike flicker of a figure in the waves, a mirage for John’s mind to spin around in wonderment.

The dusting of freckles across Sherlock's shoulders, miniscule and only barely darker than the pale tone of his skin, was visible now that John was within reaching distance of his skin. He was also flecked with - well, John assumed they were scales, but that wasn't quite right; they were freckles, too, but glinted silver when Sherlock moved, at his elbows and shoulders and the twin arches of his narrow hips. The ridges of his gills, high on the pale column of his neck, were mirrored near his ribs - but as he watched, John saw the Mer's chest rise and fall with each breath he took above water.

John longed, ached to reach out and touch, the knowledge that it was dangerous only multiplying his wish to do so. Sherlock was magnetic. John knew it would be laughably easy, now, for the Mer to lure him into the water - he was halfway to wanting to join him in the shallow waves - and yet something had subtly shifted.

“Sherlock,” John smiled, “It’s good to see you. I’m glad you found me.”

“It was not difficult,” Sherlock’s eyes scanned the expanse of the dark beach, careful and appraising. “There are only so many places a man on an island can go and stay near the shore.”

“I thought it was perfect,” John said, nodding to the creaky planks under his hands, “A run-down pier on a quiet beach, away from the town so we can talk without being seen or heard.”

“Well suited to our purposes, indeed,” Sherlock didn’t smile but his eyes were bright, approving.

“Have you ever been to Port Royal before?”

“Port Royal?” Sherlock asked, and then looked over his shoulder at the tiny, glittering lights of the port couched in the semi-circle of the cove. John swallowed thickly at the pale curve of Sherlock’s neck, still dotted with crystal-like beads of water. “Is that what you call it?”

“Ah, yes,” John replied, “Do you have a different name for it?”

Sherlock snorted, “We are not so obsessed with the naming of things as humans are; you are eager to name every rock and isle you come across.”

John laughed; it was true. “You didn’t answer my question.”

“No, I did not,” Sherlock’s grin was sharp, but not cruel – merely amused and pleased that John had cottoned on to his sleight of words, “I have seen this island from afar but not approached it before; it is not within the bounds of our territory.”

“Your territory?” John perked at the small slip of knowledge about the Mer.

“We are civilized,” Sherlock sniffed, and said nothing more on the subject.

“Do you go to many ports - or any?” John couldn’t resist asking, curious beyond measure. Sherlock’s ears twitched as he wrinkled his nose, tilting his head before replying.

“It is a risk,” he said, “A ship at sea, alone and in the dark, makes for a perfect target because it is difficult to be overheard or seen – and even then, a sailor’s claim of a Mer can be explained away as exhaustion or drink or imagination. It is not as easy to fool a crowd.”

“Even a drunken one?” John chuckled, “Sailors in port spend more nights in the local taverns than not, from what I’ve seen.”

“As do you,” Sherlock gave him a small, knowing smile, “Although you prefer to share tales rather than drinks, and you are becoming quite well known among your peers as a storyteller. It is a trait you cultivated before coming to sea, but the propensity for sailors to tell stories suits you rather well, and you enjoy it much more than any drink.”

The moonlight glittered in Sherlock’s eyes, quicksilver as he studied John with a smirk from his place on the nearby rock. From so close, John could see that his eyes were a myriad of colors: sunlight bouncing on the surface of the cerulean sea, flecks of bottle green and copper and violet, the polished steel surface of a blade. The longer he looked the more colors he found, like studying the opalescent mother-of-pearl in the shells of mussels. As the conversation flowed easily between them, John had plenty of opportunity to observe and admire.

“How could you _possibly_ know that?”

Sherlock didn't reply, letting the murmur of the waves lapping at the nearby shore wash over them. His small grin held a mischievous tilt that made John’s stomach flip and his pulse sing higher in his veins.

"Oh, go on then; impress me."

The Mer rolled his eyes. "Everything about me impresses you."

"How flattering for you," John snorted.

"You did not deny it," Sherlock said, raising his eyebrows and flicking his tail to send a splash in John's direction. John looked down to watch the spray catch one of his feet dangling over the edge of the dock, his bare toes dragging in the warm water only a few feet below. The corners of his eyes crinkled as a wry grin broke through his control. Of course Sherlock would take note of exactly what he said - and what he’d left unsaid.

"You'd know if I were lying anyways."

Sherlock snorted. “Please, James. Lying? How tedious.”

John tilted his head to the side, eyes wandering over the moon-illuminated shore. “Tedious? For you, I suppose it must be. You notice everything. It takes you - what? A matter of moments to tell if someone is telling the truth?”

“Less than that,” Sherlock grunted as he stretched before refolding his arms, propping himself up to peer at John, “The matter is more that the Mer do not lie.”

“They don’t lie?” John frowned, “But everyone lies!”

“ _We_ do not lie,” the Mer raised his eyebrows pointedly, “And before fourteen days ago, your ‘everyone’ was limited to ‘everyone human’ - though you were unaware at the time that your perspective was incomplete.”

“That might be the most elegant way I’ve ever been insulted,” John said, and when Sherlock quirked an eyebrow at him, he grinned. “Come on, really? There isn’t anything the Mer lie about?”

“We have nothing about which _to_ lie,” Sherlock sighed, affecting boredom at this line of conversation, “Not really. Our social conventions are not so - “ he waved a hand in the air, as if grasping for the right word “ - intricate as yours. Lying is not inherent in Mer as it is in humans.”

“Lying isn’t inherent in humans!”

Sherlock snorted again.

“All right,” John folded his arms, pulling his legs up to sit cross-legged at the end of the pier, “Explain to me what it’s like, then. To live in a Mer society where none of you lie. Or, where none of you feel the _need_ to lie.”

A shiver ran down the length of John’s spine as Sherlock directed the full weight of his gaze towards him. It was a bold thing to ask, John realized belatedly; Sherlock hadn’t told him much of anything about the Mer as a people, only bits and pieces that were relevant to Sherlock himself. It was undoubtedly purposeful, the subtle way Sherlock directed conversation away from these kinds of inquiries, away from anything that could be used against him or his fellow Mer.

“If you want to,” John amended, after several moments of tense silence. Sherlock’s pale eyes lingered over him, assessing, and whatever he saw made the tension unwind from his shoulders and loosened the look of pinched concentration on his face.

Sherlock’s gaze slid away and John’s heart skipped a beat; well, that was that. It was the third time they’d met, maybe the tentative trust between them was still too fragile to test with such a request. Sherlock himself had said that any question he didn’t want to answer-

“Yes,” Sherlock spoke slowly, interrupting the buzz of John’s thoughts, "You have no basis for comparison. You are curious."

John remained silent, not wanting to throw off the course of Sherlock's thoughts. As he watched, Sherlock's full mouth puckered in concentration and his lips pressed into a thin line. John licked his lips unconsciously.

“The sea is everything,” Sherlock said finally, “Everything and anything we could possibly need, we can find in the sea. Our world is immediate and expansive; we know each other, and ourselves, it is not-” His mouth closed with a swift click, and he made a soft noise in his throat, frustrated.

“Keep talking,” John urged quietly, “tell me.”

Sherlock’s deep voiced rolled over him, enveloping him, and John couldn’t help but close his eyes as the Mer spoke. “There is nothing greater than the sea, for us. It provides everything we need to thrive. We know we are just a small part of it. It is a matter of logic.”

Behind John's eyelids, the vast blue of the ocean stretched as far as he could see, striped with bars of sunlight, strong beams that flickered from the surface to the sandy bottom below. The water was deep but clear, and the rush and roar of the surf where the sea met the land was a distant purr.

"We are not a material people. We have no need for lavish clothes or weapons or coins. All we could ever need we can find around us. We hunt with our hands and teeth, and trade with each other only the most necessary and precious things.

“We live in small groups, nothing so large as the human settlements on these islands. Twenty. Forty, at most. We know each other well enough, by nature and temperament, that lying would just-” Sherlock grunted with disdain at the idea.

"It sounds peaceful," John said, smiling at the picture of a simple and calm life in his mind's eye.

John could feel the frown that radiated from Sherlock, even with his eyes closed, and his grin broadened.

"Peaceful? No. It is how we are, how we have always been. We fight with each other, occasionally, but our lives are more driven by the act of living than by bringing death. It is not purposeless."

"Is it violent? Your fighting?"

"Of course," Sherlock replied, "Territory is important. Our groups move where the currents and seasons take us, but there are still disagreements. But they are justly founded, and logical; if we attempted to be false it would be so obvious to another one of us that the claim would be dismissed."

"Really? That simple?" John shook his head in amusement, “It makes any legal system that I’ve heard of sound inefficient.”

"I was not exaggerating when I said that we have few logical reasons to lie. Humans, however..."

John cracked an eye, and found Sherlock watching him with rapt fascination. "What about us?"

"Lying is second nature to you," Sherlock said, "Your world revolves around money and material and sentiment; you get wrapped in greed or lust and try to talk yourselves out of your problems by creating new truths. What for?"

The abrupt change in Sherlock’s tone, from playful to clinical and detached, made a cold weight settle in John’s gut. Something in him seized and stiffened the hair on the back of his neck standing despite the warmth of the evening.

"That's a rather pessimistic view of human life," John clenched his jaw, "How did you form such a horrible view of us? You can't have gotten these ideas from me, though I know I’m the only human you’ve spoken to for any reasonable length of time."

"Honestly,” the Mer scoffed, "I have observed humans extensively; I have not claimed anything that I cannot base on observation."

John stared down at Sherlock, eyes pinched in a wary frown though he remained silent. He uncrossed his arms to grip the damp wood of the pier, flexing his fingers until his knuckles turned white.

“And – you think your observation is enough to – to base your conclusions off of?”

“Naturally,” Sherlock replied, calm and cool. For as observant as he claimed to be, he showed no sign of recognizing John’s increasing anger, though John was sure he was throwing signs of it left and right.

“Even accounting for individual variation,” Sherlock continued, “I’ve seen more than enough to confirm my initial suspicions as to the nature of mankind.”

“Individual variation,” John parroted, tone flat. The shiver that had started at his hairline descended over his shoulders and down his back, and he tensed at the sudden, crisp chill. As if _individual variation_ accounted for the differences in human experiences, in personality, in emotion – or belief, or morality, or creativity, or-

_Individual variation._

“You can take yourself as an example.”

John inhaled a sharp gasp, his heart stuttering in his chest. Sherlock’s focus was a bright, precise beam trained on him, a mirror reflecting the sunlight into his eyes. He blinked, his mind blanking at the sudden and intense attention, before realizing that Sherlock was waiting for a response.

“How do you mean?” he said, “I’m not – I’m no one.”

“Wrong,” Sherlock murmured, “You could not be more wrong. You are a mystery.”

John’s chuckle was bitter, this time. “Really? A mystery? I’m afraid I can’t fathom why you find me so interesting.”

“At first glance, you do appear to be ordinary,” the Mer continued, “but it is deception, and layers of it. I wonder that you even realize you are doing it. You must, with some of your circumstances – you are not truthful about what brought you to the Caribbean, even if this lie is by omission and not an outright falsehood.”

John didn’t reply, hands clenched so tight that his nails dug half-moons in the soft, salt-weathered wood under his fingers. Sherlock’s words, resonating deep and dark, sought out the cracks in his resolve, worried and whittled at them.

“You cast yourself as honorable; I doubt what you told the captain of your vessel was a full lie, but you mask your heart from your crewmates, and even they – thick-minded as they are – can feel that something in your story is not quite right. It is unusual, for one of the land to so late in life turn to the sea.”

“Not that unusual,” John retorted, but his words were brittle and without the bite he had intended. Sherlock was clearly gathering speed, and John was left to rock in the wake of his piercing observations.

Sherlock frowned at him. “But you are not just a man of the land, you were a soldier. The way you hold yourself – you pull your spine straight and plant your feet when you are threatened, verbally or physically – suggests military training. I have seen enough of that from the ships that pass through my waters to recognize it in you as well. But you’re unsteady on the deck of a ship; you must have fought on land.”

“Fine, yes,” John said, “I was a soldier, with a land regiment, before I traveled south to work on the _Zephyr_. Brilliant.”

“And then there’s your shoulder.”

“My shoulder?”

“Shoulder and leg, both. Even injured and taken away from deep combat, the injuries you sustained should have healed well, allowing you to return to your post and fight again. But they did not. Why?” Sherlock’s eyes narrowed, “Something else happened, something that disturbed the healing process. A strain on your mind that, in turn, strained your body and prevented it from healing as it should have.”

His shoulder, brought into the sharp focus of Sherlock’s attention, twinged and tingled as if it knew it was being spoken about. John fought down the urge to stretch it. “That’s-”

“Seeing the scarring itself would prove the matter, but the fact that your limp has been improving as of late is evidence enough that part of your injury lies in your mind. So: family, then.”

“My family? What does that have to do with-”

“Oh, everything. What could weigh so heavily on a young healer’s mind that it would so affect his body and keep him away from the battle he craves? With more than one traumatic wound, you would have been sent home for a time, to heal. Family it is.”

John’s blood ran cold.

“So, James,” Sherlock continued, “What about your family was it? Not only did you not heal properly, no; you could have returned to your service and continued to fight, as a soldier’s doctor. But you did not. Something tied you down. Wealth? Possibly, humans deftly weave themselves into traps with it. But you live simply now, and mend your things rather than buy something new. You are used to a life without material wealth. Perhaps something darker, then. Family always breeds dangerous sentiment, for you humans. A scandal?”

Something in John’s face must have shifted, giving him away. Sherlock’s mouth twisted into a sharp smirk.

“Oh, indeed. This is not a story you have shared with those ignorant men on your ship; it is close to your heart. Sentiment. A brother. Maybe you did not like his choices; maybe your mother liked them even less. Younger than you, as the elder sibling you felt driven to make amends, right the wrong in some w- ahh.”

Sherlock’s unnaturally bright eyes widened.

“And you did, did you not?” He ploughed forward, those catlike eyes narrowing again, “Clever, James, though stupid for attempting to erase such a heavy burden. As a doctor you knew you could find passage to these waters, take up residence on a – privateering vessel. It is a rather blunt attempt at stoppering the break in your mother’s heart. How honorable.”

“You know nothing about my family,” John heard himself say, “or what honor is.”

“Honor,” Sherlock spat, “is that what you call it? Letting your emotions ruin your body and drive you to a new life in a different part of the world – to make up for the fact that after you left to become a soldier, your brother ran away and became a _pirate_?”

The stillness and silence between them remained unbroken as John stared, insides turned to ice, at the Mer before him. Sherlock had ripped out his darkest secret, bloody and wretched that it was, from the smallest details in – in the sewn patch on his sleeve, the knot of scar tissue on his shoulder that he hadn’t even seen, in the fresh tan lines on his skin.

“Well?” Sherlock’s eyes flashed, “Did I get anything wrong?”

John’s jaw worked before he found his voice again, barely keeping his temper from boiling over, “Harry did break my mother’s heart by becoming a pirate. It’s illegal, and punishable by death. I was already home and injured when I found out, but I had little choice but to leave the army in the face of that.”

“Scandal and sentiment. Family and honor,” Sherlock was insufferably smug, the smirk on his lips driving the blunt knife of his deductions deeper into John’s gut. “You could have returned to your post as a soldier, but in her state your mother needed looking after - or the situation needed remedying in some way. You chose to follow your brother in hopes of bringing him home? To ease your mother’s worry? Sentimental, and _foolish._ ”

It was almost satisfying to snap and John seethed, grinding his teeth. “Harry is short for _Harriet_.”

The expression of self-satisfied triumph fell from the Mer’s face, to be replaced with a sneer of mixed rage and frustration. Sherlock hissed, “Sister. Oh, even better. It is little wonder that you could not tell those ignorant oafs-”

John stood jerkily, the wood planks of the dock groaning in protest. The growing breeze chilled his over-hot face, biting through the thin layer of his shirt. He clenched his fists at his sides, knuckles standing out sharply white against the tan of his skin.

“You know,” John said, voice wavering with restrained rage, “nothing about me.”

“On the contrary,” Sherlock raised one perfect eyebrow, “I think I have proven-”

“ _And_ ,” John ignored the interruption, “you know absolutely _nothing_ about humans. How can you talk about breaking a heart when – when you don’t even _have_ one of your own?”

"I don't need one," Sherlock snapped, sharply pronouncing each syllable, "To be _right_. You are human, and you have already lied to me. Do not even try to tell me otherwise, as you would be lying further. Or is your name truly _James_?”

The air left his lungs. John never felt so broken open and picked apart as he did under Sherlock’s stare in the wake of his words. He froze, swallowing thickly, as the cold crept deeper than his skin, down to an ache in his bones and a cool rush of adrenaline in his blood. The touch of fear blotted out his rage for a moment, but only enough to keep him silent and caught in the Mer’s eyes. John didn’t break their locked gazes, his eyes hardening as the anger surged and surfaced again.

“You know what? Forget it,” John said, all sympathetic thought for the Mer leaving him in a hot wave of anger that replaced the chill, “Think what you want of me. You can’t possibly understand. No amount of observing humans or talking with one will get through to you, if you talk about sentiment like it’s a _disease_.”

“And I- I am only doing what I must. But I rather like being human, and having my _sentiments_ , ta very much,” John’s voice dipped to a defensive growl, deep and quiet in his anger, “and there is much more to us than what you’ve _observed_.”

With that, John stormed off the pier, footfalls heavy, leaving the wide-eyed Mer behind him in his wake. He didn’t stay to see the expression on Sherlock’s face - and John didn’t look back.

 

•

 

It was a chilly walk up from the beach to the tavern John frequented in Port Royal, doubly so when the fire of his anger and adrenaline had banked enough to leave him shivering and sticky with cooled sweat. The gritty sand between his toes chafed less than the knowledge that Sherlock knew that John had lied about his name. The thought sent a wave of chills down his spine again, and he increased his pace. His leg was beginning to throb in the tell-tale way that indicated he was overexerting it, but the pain was secondary to getting away and leaving all thought of the Mer behind.

Land was solid; land was safe. Land was away from the churning clutch of the sea, from the roar of surf and the sight of shining, moonlit waves and pearlescent scales-

John shoved the image away, brow furrowed as he frowned at himself. He couldn’t help but turn over their words in his mind, replaying them again and again until he was almost dizzy with it, mixed emotion and tension rolling in his gut. He needed to get away, escape his own turbulent thoughts.

The cobbles of the paved main roads were a welcome sight, and John’s feet ached at the thought of a seat somewhere warm. He was drained, the weight of his emotions leaking into his limbs and slowing him down to a tired, limping shuffle. It was a relief when the thick, green foliage thinned and familiar thatched buildings came into view.

The tavern was warm and dimly-lit when John pushed open the door, a fragrant waft of air pressing into his cold face in a welcoming rush. The yeasty, ripe smell of sloshed ale and stale beer assaulted his nose, layered with the greasy scent of well-cooked food and the faintly human smell that was all but lost in the fresh, salty air of the sea. It smelled a little like home to John, being in a warm tavern on solid earth.

This one was familiar; he’d tagged along to _The Hook and Line_ many times with the crew of the _Zephyr_ early in his seafaring career, enough to recognize the carved wooden motif above the door without reading the tavern’s name, and to avoid ordering the pale, piss-like swill that came cheapest in favor for the more hearty golden ale that sailors preferred. That, or whiskey; real whiskey, too, not watered-down shite like the dregs served aboard when rations were running low.

John perched himself on one end of the bar, a bit away from a rowdy group of tradesmen at a cluster of tables in the center of the room and the murmuring bunches of two or three sailors scattered around the periphery. A few of them were from the _Zephyr_ and he nodded at them in silent recognition, tilting his tankard in their direction when it came before taking a languid sip. The pint was foamy but lukewarm, and the ale slid down his parched throat with a fizz that sharpened and pinched at the inside of his nose. He wiped foam from the top of his lip and watched the white lacing form on the inside of the tankard as the beer settled, bubbles rising and popping merrily.

The pub felt a world apart from the moonlight shore where he had walked away from the Mer - had left Sherlock staring after him as he retreated, his anger a burning knot in his chest. John’s skin still held the tingling sensation of being watched, and he stopped himself from reflexively checking over his shoulder every few moments as he sipped at his drink. Sherlock could never have followed him here; that was part of the bitter victory in walking away, onto land and to the solace of the murky, lamp-lit tavern.

How dare he.

Before, when Sherlock had turned his silver, penetrating gaze to John and rattled off the details of his life like he was reading off a list, it had only amazed John. He had stared in return, captivated by the creature that saw so much in the minute and mundane that no one else would think to notice or weigh as important. They were facts that held little weight, though, that John would share with anyone. They were facts that most of his crewmates knew, if not guessed for themselves since he had joined the crew of the _Zephyr_. Facts and details and truths, but nothing John would not admit to freely and openly.

But Sherlock saw, down to the thread and hair and blood and bone, didn’t have a filter or a conscience or a forward thought to tuck the information away rather than lay it bare – not when he could use it to get what he wanted. Because that’s all John was to him, John thought bitterly: an interesting thing to study, a specimen that he could toy with and observe from close-quarters rather than muse from afar to discover the nature of humankind. And John had walked into that, choosing to believe in compassion that Sherlock did not possess, and was now surprised when he measured Sherlock against standards that were _human_ when the Mer himself was _not_. It was foolish to have forgotten that startlingly obvious fact.

John’s anger and irritation – at himself and at Sherlock – settled like an ember in his gut, burning and aching savagely as he nursed it to a bigger blaze. He downed his ale in thick gulps, draining the tankard and setting it heavily back down onto the sticky wood as he waved to the barkeep for another.

“I swear, I saw it! White like them slipper-shells you find along the shores of them Dutch sugar islands, with dark curls an’ blue fin an’ everything! It was a mermaid!”

John’s ears perked at the sound of the word, sensitive to those syllables like he had been trained to seek out their every utterance. _Mermaid_. Of course they’d be telling tales in the tavern tonight, what with several ships full of sailors finally making landfall after almost a week at sea. It was a prime opportunity for gossip-mongering and storytelling, John well knew.

“Yer full of it, Malcolm,” another voice joined in, “You Scottish bastard, you’ve seen no Mer. Prob’ly just a big fish, and now you’re blowing smoke.”

John clenched his jaw and slid his fingers up and down his pint, collecting the thin film of water gathering there and wishing his attention would focus elsewhere, anywhere besides the conversation going on behind him.

“Oi!” There was a muffled thump as Malcolm lightly smacked his companion on the arm, and a muttered curse when beer sloshed onto the table. “I know what I seen, Jim. It was a Mer!”

“You’d be dead an’ sleeping with the fish if you’d seen one, idiot. Mer don’t let themselves be seen unless they plan on eatin’ you.”

“Don’ tell me what I did and didn’t see. They put me in the crow’s nest because of me eyes!”

“You’re a drunk fool, Mal. Last week it was a ghost ship, this week it’s a mermaid. Do you bring a spyglass or a bottle up with you to the nest?”

John rested his elbows on the bar, cupping his mouth with his palms and rubbing his eyes with calloused fingertips. It was with a twisting in his gut that he listened to his bar-mates argue about the Mer and their improbable existence. John, of all of the sailors alive and on the seas, knew the truth. The next swallow felt like lead going down John’s throat, leaving his tongue thick in his mouth and a feeling of hot, heavy discomfort in his gut. Thankfully, the sailors left the topic of mermaids when their third round of ale arrived, and John was left to ruminate on his thoughts.

The murmur of voices and the second bitter pint, now nearly empty, lulled John into a haze as he let his mind wander. Sherlock had been right on almost every point - and god, if that hadn’t been incredible. The Mer hadn’t walked him through every detail that betrayed the truth, but now that his rage had ebbed John felt stunned - awed - that Sherlock had seen so much from their three encounters, two of which he had been too far away for John to make out many details, let alone make any assumptions about the Mer himself.

But Sherlock had read his history, even the parts he had wanted to keep hidden: the injury that left him a useless husk of a man, the death-stroke to his body and honor that he pushed out of mind, but continued to seep into his person in the form of a limp. Sherlock had deduced the truth about Harry, the reason he left England to the nigh unimaginable life of a sailor, of a ship doctor. He’d promised his mother that he would find and return his wayward sibling, even though he fully knew the futility of the task.

Sherlock had even known - and he must have known, from the moment the word fell from John’s lips - that John had thrown up that small barrier of protection between them, when they first met, by giving Sherlock a false name. What had seemed like a reasonable idea at the time now felt sickeningly like a betrayal of trust. The irrationality and hypocrisy of that thought made John’s insides pitch and roll anew.

John stared down the length of the inside of his tankard, only the slick metal and remnants of lacy foam left to indicate it had once been full. There were no answers at the bottom of the bottle – or tankard – John knew that well enough. But going through the routine of visiting the pub had settled the discomfort and nervous energy coursing through his veins, at least a little.

With a wave of his fingers, John ordered a third pint, and it was set in front of him without preamble. He nursed it through his lingering anger and unease, churning Sherlock’s words in his mind. It was all too muddled for him to make heads or tails of how he felt, besides the sour taste in his mouth and the ache of exhausted frustration in his chest.

He returned to the _Zephyr_ with a pronounced limp, answering in clipped syllables to anyone who asked him how he fared, and headed straight for his cabin. He collapsed into his small bunk with a deep sigh and scrubbed his hands over his face again, willing the pinched, tight sensation between his eyes to go away.

The evening hadn’t been at all what he had planned or hoped.

He spent the rest of it in muted darkness, tossing and turning and unable to quiet his thoughts enough to sleep.

 

  
•

 

John woke to bright sunlight streaming through his window, faced with a full day in port with little to do and a head that felt like it was stuffed with cotton. His sleep had been too fitful to be restful, and it left him aching just as much as the night before. He massaged the bridge of his nose as he sat up, casting a wary glance at the compass that still sat on the little table at his bedside. The needle skittered and swung back and forth, insect-like in its constant movement. John glared at it, but it never stilled.

He left his cramped cabin for the sunny deck of the _Zephyr_ , sure to keep out of the way of the deck-hands that were swabbing and polishing until the wood gleamed and shone. Gulls circled lazily overhead, riding the eddies of the gentle breeze and floating effortlessly, as if cut from fine white paper. The sky was endlessly blue, pale against the bright, gem-like surface of the sea, and the sight of the new day filled John with a fresh calmness. It wasn't hard to find a quiet corner to sit and enjoy the tranquil murmur of the early morning; the mood of the crew was light, if not tired because their nighttime revelry in port, and John felt the tension begin to unwind from his shoulders.

Sleep – the little of it John had gotten – had distanced him from the heat and anger of the previous night, and his head felt clearer than it had been at _The Hook and Line_. His heart beat a steady rhythm in his chest, not elevated from rage, and he took a deep breath to exhale slowly. Looking out over the horizon at the pastel colors of the beach and placid town, John dug into the ache, tried to pick away at his discomfort and anger to look beneath.

Sherlock had told him, outright, that he found John fascinating. _A mystery_. John didn't see himself as half so interesting as Sherlock claimed he was. But it made sense, he mused, that Sherlock would catalog and pull apart every detail he could, to try to understand what made John so captivating. He couldn't blame Sherlock for that; John himself was intrigued beyond measure with the Mer. The difference was that John asked his questions forthright, whereas Sherlock could observe and deduce the details for himself. They learned more about each other with every encounter, though in different ways. John shifted his weight from foot to foot, turning the idea over in his mind.

The deck-hands shooed him away from the forecastle deck when they needed to wipe and varnish the railings as well as the boards underfoot, so John wandered down to the galley to assist Stamford. There was really little he could do for himself; John kept his own medical supplies well-stocked and well-organized, which left him plenty of time to do as he pleased in port. Today, he really didn't feel like walking the charming streets of Port Royal or returning to his suffocating little room, and he felt rather cut adrift with the extra time. But Stamford was a cheerful fellow, always open to an extra hand and a good conversation, so John let his feet lead him down the narrow stairs and aft, to the galley.

Stamford greeted him with a smile and hearty clap on the shoulder, glad of the help that John offered. The most that needed doing was sorting the incoming crates of cargo and bringing the last few boxes in from the pier outside, but John was glad for the physical labor. His leg twitched and ached, more pronounced that it had been in weeks, and it stung to remember Sherlock’s cutting comments about it. Stamford didn't notice his limp, or at least he didn't say a word, so John let his hands do the work as his mind was occupied with thoughts of Sherlock.

They worked for the better part of the morning in easy silence, interrupted by the clattering and thumping of movement above and occasional comments about their task. More than once Stamford had to repeat his instruction before John caught on with what he was supposed to be doing, to John’s flushed embarrassment.

“You've got something on your mind,” Stamford set a hand on John’s shoulder when they had finished. He didn't pry, and John gave him a tired smile that didn't reach his eyes.

“Is it that obvious?”

“Only because I had to ask you three times to move the crate of onions,” Stamford chuckled, “Maybe take a walk into town, yeah? Clear your head a little?”

John shook his head, “Not really in the mood, mate.”

“On a beautiful day like today?” Stamford said, “At least get some sunshine while you can. Too soon we’ll all be at sea and cooped up again, or there’ll be a storm and we’ll have to batten down the hatches. Believe me, it’s good to stretch your legs while you can.”

“Yeah, I’ll- yeah,” John sighed, “Thanks, Mike.”

Stamford waved him out into the crew quarters and John lingered in the narrow hall, unsure of which direction to go. The thought of his cabin made his stomach clench, but there wasn't anywhere else he needed to be. Maybe a walk would do him good after all.

John’s feet knew the way down the shipyard pier and into town. It was just noon, the sun high overhead and comfortingly warm against the back of John’s neck, and the commotion of human activity was a pleasant background noise in his ears. He purchased bread and meat with a few spare coins and sat at a squat bench to take his lunch, chewing as he looked out over the crystal blue of Port Royal’s bay. His mind was already treading the worn path it had been circling all day.

The heart of the matter was that John hadn't expected Sherlock to see so deep into him, to dig up the secrets he held close, kept in his bones. He hadn't spoken to a soul about his – about _Harry_ since leaving England all those months ago, when he had decided to come south and learn what he could about her disappearance and subsequent turn to the life of a pirate. His mother, heartbroken, had urged him to, but it was just as much his own sense of duty to his family that had pushed him into making the voyage. It wasn't like he could continue to be a good soldier – or doctor – with a bum leg and shaking hands.

He couldn’t even say he had been completely surprised to learn of his sister’s flight. She had never quite fit in with the vision of the woman his mother wanted her to be; Harry played rough with the boys all through childhood, and ran and fought when she had been urged to take up the pursuits of the fairer sex. The two of them had been inseparable in youth, a connection that made the different expectations of them all the clearer as they grew. Harry had refused the role set before her and forged her own path. Though John couldn’t approve of the piracy - if that was what Harry had truly taken up - he couldn’t deny that escaping their mother may have been for the best. That didn’t change the fact that he had to see her for himself –make sure that she was alive, and hopefully happy in her chosen life.

John balled his hands into fists in his lap, squinting in the bright light. Following Harry had ended up being the best thing he’d done, in the wake of his injury. Well, maybe not the best thing he’d done. Meeting Sherlock – there was nothing that came close to the experience of meeting the Mer. John’s stomach clenched and churned, knotted with tension as a slow-dawning light broke over his thoughts. 

He’d walked away from the most amazing thing to happen since - _since_. The one thing that he looked forward to, during the locum day-to-day work about the ship that kept him occupied, but not interested, in the world around him. There was no guarantee he would ever see Sherlock again; John would have to return to the docks, to the _Zephyr_ \- to the ocean, eventually, but Sherlock had no compunction to stay if John broke their agreement or made it clear he had no interest in seeing the Mer any longer. It was too much of a risk to try to see a human that could so easily reveal his secret. Hell, even now John could spin a tale - the truth - and reveal the secrets he had learned from the mouth of a Mer in the flesh -

John’s gut rolled again at the thought. No, no; he hadn’t lied when he told Sherlock he was a man of honor, and he wouldn’t betray the Mer’s tentative trust or the accord that they had forged between them. But - what if Sherlock did disappear forever? All John would have left would be the stories. No matter how much he knew to be true, no one would believe him anyways. John’s fingers flexed and his throat tightened as he fought to swallow the sudden, punch-like ache.

The routine he had carved for himself, the three months he had spent on the _Zephyr_ , wasn’t comforting him like he imagined it would. The sea was fine, the work was fine - it was all _fine_ , but it wasn’t interesting. He couldn’t think of anything he wanted to do, anywhere he wanted to go. The thought of the stale-warm, choking smell of beer at the pub or the tight walls of his cabin made him shudder, and even the beautiful sight of the land and sea meeting at the bay below was no comfort now that his mind was fully tangled with his brooding thoughts. He felt displaced, foreign in his own tanned skin. It was all suddenly too bright, too hot, and he buried his face in his hands, scrubbing at his skin to distract himself from the leaden weight in his gut. What he wouldn’t give for the cool of night, a breeze at his back and the fresh scent of nearby waves.

He’d rather be on the beach, his toes dripping ripples into the waves, grinning and arguing and conversing with - with Sherlock. John’s pulse jumped.

Beautiful, incredible Sherlock, who would suss out a man’s past and pain with a few glances - who knew more than he ought to about humankind even if he didn’t know all the proper words to describe it. Sherlock, who was undoubtedly the most interesting thing to happen to John and, John was beginning to realize, the truest friend he’d had since he had left the army on a makeshift stretcher.

John stood shakily, hoping to walk off the tension at the base of his spine and the discomfort in his belly. His leg was sore from the earlier labor, but he was stubborn in believing a walk would stretch it and lessen the pain. Being in port meant he could walk the town rather than pace the tight corridors of the _Zephyr_ ’s lower decks.

Sherlock couldn’t help the way he was, that his eyes saw everything and his mind connected all the dots into a picture he couldn’t look away from. John frowned. It wasn’t inherently malicious on Sherlock’s part; it was part of who he was - and an incredible talent that he had cultivated from his natural tendency to observe. Surely if he was here, on the bench next to John’s, he would be able to tell John more about the men and women around him than John had managed to learn in the months of regular visits.

Oh, and wasn’t that a tempting fantasy; Sherlock beside him, long and lean and dressed like a sailor - with legs to match the lithe, muscled torso John had seen above the waves. John would quirk his eyebrows in the direction of the pair of traders lingering in front of the butcher’s door, bent close in private conversation. _Do them_. Sherlock would lean in as they strolled, breath warm against the side of John’s face as he murmured into his ear. _They are smugglers, bartering to exchange goods and form a tentative alliance. Look at the ring on his finger, the grit under his fingernails; he has been to the Far East recently, dealing with spices from the traces of powder on his cuffs and moustache, and smuggling to avoid the taxes judging from -_

John shook his head to dispel the vision. His imagination had easily, flawlessly cast Sherlock in the role of a close friend, if he were human; but there was no saying that couldn’t be true as they were. Sherlock was callous, unknowing and uncaring of human social graces, but he was honest and that was what John valued the most. He could overlook and - well, at least attempt to teach - Sherlock about the rudeness, but he’d never want Sherlock to stop being who he was, or start lying to him. Sherlock was extraordinary, and John couldn’t imagine him any other way now that he’d gotten to know the Mer.

And – John shivered – there was the growing thread of attraction between them that he purposefully kept pushed to the back of his mind. Sherlock’s ethereal beauty was only the start; his sharp wit and sharper mind never failed to entrance John. Every encounter left him with a simmering heat in his blood, the tempting promise of Sherlock’s body all the more magnetic because of the soul it housed. But it went both ways – Sherlock was equally drawn to him. John didn’t know if he was the _seducer_ or the _seduced_. Perhaps it was a little bit of both; he flushed hot at the thought.

John looked up and found that his ambling circuits through Port Royal’s cobbled streets had brought him back to the door of _The Hook and Line_. There was laughter and the bready scent of yeast from within, but John suddenly knew that wasn’t where he wanted to be.

He wiped his hands on his trousers to rid his skin of the lingering grime of sweat and sea. They weren’t shaking.

When the sun had set he would go to the beach, John decided. Already the sky was beginning to blush where it met the horizon, as the afternoon waned into early evening. John hoped against hope that it wasn’t too late to find Sherlock again and make amends for letting his anger rule his head. He left the cheerful shops and curtained windows of the town behind him, blood thrumming with every step. He set out for the Zephyr, intent on returning to the shore to make amends that night.

 

•

 

It was much darker when John returned to the shore, the wind whipping shadowy clouds in sinister shapes across the face of the full moon. The shore was inky-dark and lit with cool beauty in turns, flickering with mottled moonlight as he approached - like it was somewhere between real and imagined.

The sand was still cool on his bare feet, and the solitary pier the only dark shape on the stretch of lonely land before him. The sea was not as calm as he had left it; the wind whipped it into a froth, and the waves gnashed like teeth at the steady posts of the pier. Water seethed and seeped up between the crooked planks, turning the wood dark and slick. John left sandy footprints as he walked the length of it, pace even and steady despite the press of the wind against him and the roar of the endless surf.

He stood at the end of the pier, watching the small silhouette of the _Zephyr_ across the bay, dwarfed by the hilly coastline behind her. It was studded with the lit windows of faraway houses - two miles at most, John guessed, maybe three - but the sleepy port felt like a lifetime away from the thudding of his heart, from the extraordinary circumstance his life had become.

His had body slipped into the rigid, straight-backed military pose effortlessly and unconsciously as his had mind wandered, and John forcefully shook himself out of it. Some habits were long to linger. With a deep breath he folded himself and sat cross-legged, keeping his toes out of reach of the excited waves.

There wasn't any turning back from this, he thought. One could no more easily take back actions as one could take back words; Sherlock wouldn't stand for insincerity or mollification, but John had to prove to him that what he said was true. He had to prove that Sherlock was both right and wrong - right in that John had lied, yes, but wrong in his assumption of intention. Maybe, along the way, he could manage to prove him wrong about human nature, too.

John swallowed against the nervous tightening of his throat, tension in the clench of his fingers over his kneecaps, trying to stay calm.

"Sherlock," he called over the sea and wind.

There was no response beyond the rumble of the ocean in his bones, the fading and flickering of the full moon. John willed himself to ignore how ridiculous he looked, calling into the night after a myth.

"Sherlock!" He shouted, letting some of his desperation leak into his voice.

The boards beneath him creaked and groaned at a sudden flux of dark water, surging deep and fast in towards the shore. The moon burst forth from the clouds and the beach was bathed in milky light. John scanned the silvery water for movement against the rush of tide.

Sherlock emerged from the dark water silently, black curls dripping and glistening like they were wrought from the sea itself. His eyes were flinty and nearly colorless. The light illuminated his silhouette and caught on the miniscule scales peppering his skin like mirrors, his edges iridescent and mirage-like.  He was ethereal and wild; if John hadn't seen him before he would have thought he was a sea nymph borne of the foam and surf and Neptune's will.

“Sherlock,” John nearly sighed, relief flooding his body at the sight. Sherlock was beautiful, yes, to the point of distraction, but it was reassuring that the Mer had come to him again - he’d still have to say his piece to repair any damage he’d made to their tentative friendship.

The Mer didn’t reply right away, his face chiseled and unmoving like he was carved from marble, gorgeous but expressionless. His eyes locked with John’s after a cursory glance about his figure, lingering on the soles of his feet and a spot on his shirt - John resisted looking down, but he must have dripped something that revealed his destination and what he had done with his time spent there.

“I would return the favor of calling you by your name in greeting,” Sherlock replied finally, “but as I do not know what it is and refuse to use the false one you supplied me with, I will simply ask - what is it that you want?”

John shifted, the muscles in his neck and shoulders tense as he unconsciously held himself at attention, drawing himself up to say his part.

“I - wanted to apologize,” he said slowly, meeting Sherlock’s gaze with his own, “About what I said. You were right, the observations you made. I don’t like revisiting my past, especially because I didn’t get to tell you about it on my own terms - but you were right about nearly everything.”

Sherlock was silent, assessing.

“It wasn’t fair of me to say those things, either,” John continued, “I was angry and - well, maybe partly rightly so, but it wasn’t on to say those things about you. About, um. Not having a heart. I don’t believe that’s true. I’d still like to continue our acquaintance, if you’ll have me.”

John watched as Sherlock’s eyes flicked back and forth between his own, reading the stark truth on his face - he didn’t guard against whatever Sherlock saw there, the tide of emotions and the fluttering hope he held in his chest that he hadn’t bollocksed up the one thing that made him feel truly alive.

The corner of the Mer’s mouth twitched upwards, “Nearly everything?”

John couldn’t stop the smile that broke out over his face, “Yes, nearly.”

“Anything besides...’Harry short for Harriet?’” Sherlock asked, his full mouth pulling open in a wry grin.

“Well…” John rubbed the back of his head, brushing through the short strands as he gathered his thoughts, “you...rather implied that I was intentionally deceiving you by not giving you my real name. It was more superstition and caution at the time, not an attempt to undermine our friendship by being untruthful or what have you.”

Sherlock tilted his head, considering, “That is surprisingly wise of you,” he murmured.

“Yes, well,” John slapped his thighs, leaning forwards, “that’s what you get for having a superstitious Scottish mum, I suppose. She would tell us stories about fairies-”

“Fairies?”

“Um, fairies are small winged beings, human-shaped but tiny and vicious, with magical powers and a penchant for kidnapping children and exploiting the loopholes in their contracts with humans. Especially if you don’t leave them a tithe.”

Sherlock didn’t look any less perplexed at his explanation, so John ploughed forward, “They had particular power over you if you willingly gave them your given name. Mum wouldn’t tell any story without reminding us that we should never give our names if we weren’t sure it couldn’t be used against us.”

“So you gave a false name as a reflex for self-protection?” The Mer rolled his eyes. “As I said, surprisingly intelligent.”

“I should take offense to the ‘surprisingly’ part,” John said mildly, still smiling.

The soft lapping of the waves against the beams of the pier were suddenly louder as silence settled over them, Sherlock observing John with a wary, reluctant kind of trust. John didn’t blame him; John could have gathered a riot of villagers ready and willing to catch a myth and expose it to vicious attention. But he didn’t, and John was beginning to gather that for all the Mer were truthful, they were not a trusting clan. The subtle cracks in Sherlock’s bravado revealed a vulnerable, cautious creature unused to humans, as much as he puffed himself up and used his wits and cunning.

“You did not- ” Sherlock began quickly, slipping closer to the pier in a silent ripple of water, “You did not reveal me, or betray me in your anger.”

“I was angry,” John agreed, “at you. Then, I was more angry at myself, for the things that I said. You can no more stop yourself from being who and what you are than I can stop myself from being who and what _I_ am; I was wrong of expecting more than that of you. But I didn’t betray you. I’ll still prove you wrong.”

“On what point?” the Mer said, reaching out an arm to curl it around the base of one of the piles, where the wood entered the water. John’s pulse thrummed in his throat; Sherlock was definitely close enough to see it, and from the Mer’s smirk John knew he had. He was suddenly glad, despite the rapport they’d built, that he had chosen to keep his legs tucked underneath him, not dangling over the edge of the dock.

“Not everything humans do is driven by greed or malice or hate,” John’s hands fell from his knees, bracing on the soft, supple wood at the very edge of the dock, “If nothing else, I need to convince you of that.”

Sherlock’s pearlescent eyes didn’t leave his, the raw energy of their connection causing the hairs on the nape of John’s neck and his arms to stand on end.

“Do your best,” Sherlock murmured softly. His pink lips parted in an exhale, rosy against the pale, moonlit hue of his skin and shining with a dewy wetness left by the waves.

“I will. I’ll give it to you freely,” said John, tone quiet and trusting, “my name. I give it to you freely.”

Sherlock’s eyelids fluttered and dropped, half-lidded as John leaned closer. His eyes jumped to look up into John’s and then darted down, to the curve of John’s mouth, eyelashes dark and casting shadows on the curve of his freckle-dusted cheek.

John reached out, left hand cupping the strong curve of Sherlock’s jaw to draw him just close enough for John to breathe in his scent, for his lips to barely brush against Sherlock’s as he spoke.

“John,” he whispered, “my name is John.”

On the last syllable he pressed his mouth to the Mer’s, blood roaring in his ears like the sea as they made contact, and his world narrowed down to the sensation of soft, wet heat.

 


	4. Chapter 4

**Summary for the Chapter:**

> He threw the last stone in his hand, hearing two soft skiffs as it brushed the surface of the water in its flight – but no final splash came.

**Notes for the Chapter:**

> At last, here is chapter four of 'and the sea so deep'! At over 12k words this one is quite the beast. It took a little longer to wrangle into shape than I had hoped, but series three also happened in January, so I hope you can forgive me the delay!
> 
> Once again, all my love to [Meg](http://forsciencejohn.tumblr.com/) and [Allison](http://wearitcounts.tumblr.com/), without whom this story would be much worse for wear. I cannot say enough about how lovely and patient they are.
> 
> For fic progress updates and writing snippits, you can find me on tumblr as [venvephe](http://venvephe.tumblr.com/), where I update quite frequently with my current projects.

_" - and I feel queerly drawn toward_

_the unknown sea-deeps_

_instead of fearing them."_

_\- The Shadow Over Innsmouth_

 

 

 •

 

Sherlock’s lips felt as lovely as they looked; full, silk-wet and surprisingly warm. The perfect swell of his lower lip was soft, lush where it was pressed against John’s own. John was achingly aware of the smallness of his own lips in comparison, but delighted in the delicate arch of the Mer’s cupid’s-bow, the drag of his cheek against John’s nose, the lace-like sensation of his eyelashes fluttering as Sherlock blinked, once, twice. Sherlock didn’t kiss back, stiffened by surprise at the intimate contact, though John could feel his pulse pounding at the corner of his jaw, where John’s fingers framed his face. John pulled away, opening his eyes with a small smile on his heated face.

Sherlock looked devastated. His pupils had dilated, his irises scant but pearlescent rings that flashed in the dim light. His eyes were slightly glazed, too, faraway even though he was staring at John. A healthy flush crept down his cheeks, turning them a ruddy pink in contrast to the silvery, pale cast of the rest of his form, and John could feel the heat radiating from the surface of Sherlock’s flesh. His breathing was ragged, every exhale fluttering over John’s clammy, over-warm skin, and rustling the messy curls that spilled over Sherlock’s forehead and around his ears.

“Sherlock,” John murmured, unconsciously stroking the sharp expanse of cheekbone under his thumb. At the sound of his name, Sherlock quivered and tensed, blinking back into focus as if he had been underwater. His eyes twitched from John’s own to the wet, reddened state of John’s lips, following John’s neck to shoulder to arm, to the hand cupping his cheek with startling rapidity. With a jolt like he had been struck by lightning, Sherlock’s eyes snapped away from John, turning his face enough to dislodge John’s hand from his skin. The absence of contact left John suddenly cold.

“John,” Sherlock swallowed thickly, eyes wide and vulnerable. The cast of the moonlight against the plane of his jaw suddenly made him paper-thin and fragile, brittle bone more than smooth marble. He stilled, gaze locked with John’s, and a tremor passed through his body in a way that made the hair on the back of John’s nape stand on end. With barely a splash, Sherlock disappeared under the dark water.

John’s world titled. He tipped backwards, reeling from the unexpected disappearance and nearly losing his balance. He almost fell back onto his elbows before righting himself, but immediately scrabbled to lean out over the water, to try to see anything in the dark but clear water. The waves churned and whorled, gauzy foam obscuring the surface and revealing nothing beyond depthless black.

The Mer had vanished from underneath John’s fingertips.

His lips buzzed at the memory of Sherlock’s - not slimy or fishy at all, just moist and warm, plush but firm. Arousal sang down John’s spine; he swallowed at the sensation of his prick starting to take interest, heat pooling in his gut despite the cool bite of the night air. From what he had seen of the Mer’s dilated pupils and blushing face, Sherlock had had a similar reaction. Maybe that was what had spooked him away.

Somehow, John knew Sherlock wouldn’t be returning to see him that night.

Had he affected Sherlock, as Sherlock affected him? Not just with the physical intimacy of the kiss, but deeply, down to the quick with every glance and exchanged word - with something rolling in the gut and gnawing at heart and mind alike? The deafening rush of blood in his ears that sounded like the tide, that he would willingly step into the wave’s crush?

The adrenaline and nerves in his system faded and John stood, slowly, on weary feet. With one last look at the white-capped waves, he made his way off the pier and down the shore, back to the warm wood confines of the _Zephyr_.

He didn’t limp.

•

 

The _Zephyr_ and her crew remained in port for two more days, exchanging cargo and refilling their supplies for their next route patrolling the islands. They were due to return in two weeks’ time, after sweeping north and then south again, all the way to the British Indies and the Lesser Antilles. Lestrade briefed them on the latest reports; pirate activity was heavy near Tortuga, as always, and the rum-smuggling runs up and down the islands to Hispaniola were gaining strength. They’d have to keep a wary eye and take whatever action they could if they came across a pirate frigate.

John didn’t balk at the thought; he’d been a soldier, he’d seen fighting and the wounds it caused: the dulled crunch of broken bones, the snick of a blade through flesh, the mess of meat and muscle left in the wake of a shattered bullet. John was no stranger to the physical toll of war. But the thought of being on a _ship_ in battle, where cannonballs could rip through the sturdy planks that formed the only barrier between him and the gaping deep of the ocean - John wasn’t delighted by the idea. In his three months aboard the _Zephyr_ it had never come to that. The pirates they had encountered led to scuffles and minimal bloodshed thanks to Lestrade’s expertise and the skill of his crew, never any damage to the ship herself. John was grateful for that, and hoped his luck continued.

John watched the island shrink in the distance when they left Port Royal, a diminishing spot of dark green on the blue-on-blue of the horizon, until it was out of sight behind them. John caressed the stretch of wood railing he leaned against it, silently hoping they were in for a tame journey. From his view on the stern deck, John watched, mesmerized, at the frothy, seething churn of water that the ship left in her wake. The sea had already changed from the crystal, sapphire-blue of shallow water to the dimmer and darker deep-blue as they sailed away from the comfort of land. The _Zephyr_ cut through the calm waves, spitting mist and foam to either side of her bow, her wood gleaming in the mid-morning light and sails pregnant and full with a healthy northern wind.  

John made his way below decks, greeting the crew he hadn’t seen in several days as he walked by with a bounce in his step. His crewmates had been busy, aboard the ship or in the bustling port town,  preparing the ship for her next voyage. Some of them had had time to themselves, like John; he had no doubts as to where some of them had spent their hard-earned silver. As much as any of them loved the sea, there were some comforts that only solid land could provide. The Zephyr felt brimming-full, swarming, now that all its wayward workers had returned for their journey.

After his encounter with the Mer, John had continued to follow Stamford’s advice, and took to wandering the beaches that were within walking distance of the port.  He kept a sharp eye on the play of the light on the surface of the water, the bright flickering of scales catching the sun as fish flitted in shimmering schools and the splash of sea-birds surfacing with their struggling catch. He hadn’t seen Sherlock again in Port Royal, but it calmed John a little to be near the beach, to use his muscles to walk off the nervous energy that built up during the nights like static under the surface of his skin. His brain played and re-played the night of the full moon: the sensation of his lips and Sherlock’s, joined for a brief moment of intense contact, the brush of Sherlock’s cool nose against his cheek, the dark curls like salt-stiff silk running through his fingers. But more than that, John’s mind cast back to the comfortable conversation, the banter and discussion of so many things - before Sherlock had flayed him open with his cutting observations, and John had pushed away. There was no saying what the Mer thought of him now. John would have to wait for Sherlock to come to him - if that was to ever happen. His gut twisted at the idea that it wouldn’t; the magnetic pull between them was strong, almost hypnotic, and John clutched close the belief that he would see the Mer again.

•

 

They made landfall on the fourth day from Port Royal. The island was just a slip of land, wide stretches of white sand that rose into a hill of lush green, with a sleepy island town nestled into the eastern inlet. It was so small as to be untouched by the influences of pirates. It was only a small stop, to wash and refill barrels and take shelter in the calm bay before sailing onward in a five-day stretch out at sea.

Compared to Port Royal’s constant murmur of human voices and footsteps against stone, it was pleasantly quiet, punctured with birdsong during the day and a chorus of frogs’ calls at night. The crew of the _Zephyr_ made most of the noise in the harbor when they laid anchor and docked in the village, the silhouette of the great ship dwarfing the tiny town around it. The friendly locals came out to greet them as they rolled out their empty barrels to be refilled. Everything seemed over-loud in the quiet of nature, and it made the hair on the back of John’s neck stand on end. He felt watched.

In the nights since John had seen Sherlock, the moon had started to wane, growing smaller and smaller by the day as if someone was slicing off pieces of it in hungry increments. Brighter stars shone through the hazy fog that had settled over the scattered houses of the island town, muted to a soft glow high above. Gold light from the tavern windows and the portholes of the Zephyr herself shot into the darkness in warm beams, illuminating the cove’s water a murky green. The air felt thick in John’s lungs as he slipped away from the ship, needing to stretch his legs more than just pacing up and down the deck under the watchful eyes of the skeleton night crew.

John followed a path through the dense green palms until the town and the hulking mass of the _Zephyr_ with her golden light were out of view, retreating to the cool blue darkness of the starlight and the hush of leaf against leaf. The trees thinned and gave way to a rocky beach lit by moonshine, granite emerging like teeth from the brown-pink sand, broken shells scattered where the waves lapped at traces of older foam. The sand was rife with ocean debris that cut at John’s bare toes, his worn shoes abandoned where the path through the jungle-like thicket of leaves widened into the beach itself.

John wormed his toes into the warm sand, picking aside bits of crab shell and moon-bright mica and sea-smoothed pebbles. There were little creature comforts like this that he couldn’t find aboard a ship, confined by man-made walls in a room barely big enough to breathe in. He relished the myriad sensations, the different textures against his skin as his mind uncurled.

With a little pile of pebbles in hand, John moved closer to the water, intent on skipping them across the placid, mirror-like surface. Very few of the stars were reflected in the ocean, what with the fog, but it was eerily still, more lake-like than sea, with only the barest of curling waves lapping at the dark, wet sand where land met sea.

It had been years since he’d done this, but John knew the motions; he selected one rock, flat and mostly rounded, and ran his fingers over it to remove the lingering traces of sand. He let it rest in his cupped hand, feeling the cool weight and shape of it in his palm, quickly warming to the heat of his skin. Drawing his arm back, he let the pebble loose in a long arc, and it skipped three times over the water, fading out of sight in the fog and the darkness before sinking into the surf with a high-pitched plop. John smiled.

The second rock hit the water at an off angle and immediately dropped in without skidding across at all, but the third skipped three times, and the next four, and John grinned to himself. He stretched his shoulder, the muscles now happily warm from the easy exertion. He was pleasantly surprised at how compliant and painless the damaged tissue was being. It was easy to reach down into the sand and gather another little handful of smooth, flat stones. The only sounds on the beach were the rustle of dune grass in the faint breeze and the sloshing of the gentle waves as they broke against the shore, as well as John’s even breathing and the melodic plopping of pebbles into the sea. The occasional frog called into the night from the dense wood behind him, but other than that John was alone, but contentedly so.

John pinched another pebble between two fingers and threw, watching it disappear into the fog but counting the number of faint splashes he heard until the fateful plop - six, that time. He grinned, rotating his shoulder and cataloging the usual stretches and aches, fewer now that months had passed since the near-fatal injury.

He threw the last stone in his hand, hearing two soft skiffs as it brushed the surface of the water in its flight – but no final splash came.

In a flash of adrenaline John’s senses snapped to high alert, his eyes scanning across the small cove, but the fog blanketed most of the water from view. An unnatural, tense silence settled over the shore; the breeze stilled and even the trees seemed frozen in place. It was the silence of a forest when a tiger had stepped into view. The water around John’s feet had stopped lapping with gentle waves, motionless and noiseless. John breathed through his nose to stay as quiet as possible, his own heartbeat thunderous in his ears, muscles taut and ready to respond in fight or flight.

“So this is the man he chose,” a feminine voice rang out clear and harmonious from the fog, “I cannot say that you are what I expected to find.”

John’s eyes flicked back and forth, trying to find a shape in the opaque cloud of fog that crept closer towards the sand - towards him - in pale, inching, finger-like movements.  His ears perked at the delicate, hushed sound of moving water, trickling and dripping alarmingly close to the shore.

A figure emerged from the fog in front of him, slowly coming into contrast out of the flat grey mist, spectral and ethereal. She moved with lithe, sinuous movement, stretching her arms and rounding her shoulders as she swam forward, pale skin ghostly in the aqua-blue water. She was, undoubtedly, female; John’s eyes skirted down her lean form, the curve of hip and swell of breast visible under the water, and his pulse spiked when he saw the gunmetal-grey-silver of scales where her legs should have been.

When she was no more than a stone’s throw away, she hoisted herself onto one of the rocks protruding from the unnaturally calm water, leaning forwards on her crossed arms with a smile of amused condescension. The regal arch of her back put her breasts on display, and John intentionally kept his eyes trained on hers, achingly aware that this creature was sharp, and strong, and undoubtedly wild.

Dark, luscious curls cascaded down her bare back and across her shoulders, ringlets dripping and casting rivulets of water down the lengths of pale skin. Her eyes were blue-black and almond-shaped, hungry with a naked, predatory curiosity. Unlike Sherlock – the only Mer John had seen, and his only point of comparison – her features were softened, more feminine, full lips and cheeks and strong, commanding brows.    But for all her unusual, unearthly beauty, John couldn’t help but stare at the history written on her skin. A jagged scar cut across her upper arm, the flesh raised and silver where it had healed. She was pocked with similar marks - on her fingers and stomach and shoulder blades, punctures and cuts and rips that had all healed but left their mark. Parts of her tail, too, were crossed with scars; the scales that had regrown were smaller, and sometimes fused together over the old wounds. The edges of her fin were tattered here and there, like a battle-won flag. A bright fish hook dangled from one ear, a single loop of lumpy, mismatched pearls around her neck her only other decoration, and the Mer kept John pinned under her gaze. John recognized the look; it was one of a warrior.

From one clasped hand she revealed the pebble John had thrown, rolling it between finger and thumb and examining it as if it were a precious jewel. John knew that he was the sole recipient of her attention, the cool trickle of adrenaline still pulsing in his veins. The mischievous tilt of her mouth hit another note of recognition in his brain, and all the air left John’s lungs when the revelation crystallized in his mind.

John gasped, “You’re-”

“Do not say it,” the Mer said lightly, glancing at him with a raised eyebrow, “My name, that is. Despite the circumstance and the fact that I have already appeared to you, it _would_ be calling me, and I would not want to have to eat you on account of a...erroneous choice in words.”

John shivered, flexing the fingers of his left hand. “But - you are…?”

She held his gaze, unfaltering, “The mother queen of the Mer, yes. Plunderer of treasure, devourer of men. Are they still saying that about me?” Her grin grew razor-sharp, the delicate points on her teeth glinting in the muted moonlight.

“Um,” John said, “Yes, they do?”

“Good,” Aeserena flicked away the pebble, settling on her rock and gazing at John with a smirk, “Though men should be more careful with how they use my name, even when telling my stories. They do not know how names have power. You do.”

John clenched his jaw, and the Mer continued, “Yes; you do. You knew not to give your true name to my son.”

“I was always told to- ”John began, ready to reiterate the tale of fairies, when his mind snagged on the word – “Hang on, _son_?” John gaped, then snapped his mouth shut when Aeserena laughed, the sound harmonic but chilling him bone-deep.

“Sherlock is quite a sight, is he not? He inherited most of his qualities from me,” she gestured at the exposed curves of her pale skin, interrupted by scars, even more stunning because of them. “But amongst our kind he is - singular.”

“He’s incredible,” John said, his hackles rising at the tone Aeserena had used, at the sharp consonants and the click of her jaw biting out the final word.

“Oh, he is,” Aeserena agreed easily, giving John a slow, knowing smile. “But I think you do not quite understand his circumstances. Male Mer are rare. When I said _singular_ -”

John frowned, “You mean he’s the only one?”

“Very few like him have come before or after,” she said, combing through her drying curls with long, sharp-nailed fingers. “It puts him in a rather difficult position.”

“How do you mean?”

Aeserena met his eyes, letting the quiet stretch thick between them. “You know what the Mer do, _James_ ,” she said quietly, “but not all of the dark details. Neither does Sherlock. For as brilliant as he is, he has blind spots.”

John frowned, growing tired of veiled language and vague allusions. The thick fog choked out the outside world, trapping him at the Mer’s whim, and John felt himself start to sweat. “Say what you mean.”

“He is dangerous,” she hissed, lips pulled back in snarl and eyes flashing, her curls rippling as she leaned forward and bared her teeth at John.

“I happen to like dangerous,” John replied darkly, shifting on his bare feet, “and I can’t see how this is any of your business. Who Sherlock decides to befriend, that is.”

“I’m his mother and leader,” Aeserena spat, “he is my business.”

John chuckled. “If you think he can be _led_ anywhere, I’m not sure we’re talking about the same person.”

“Ah,” the Mer exhaled, eyes narrowed, coiling into herself and swishing her tail in the shallow water. “You are loyal very quickly, are you not?”

“I wouldn’t call it quickly,” John hedged.

The Mer leaned back, studying John  shrewdly. “Sherlock told you that we Mer do not lie,” she said, “so let me be clear: even to us, Sherlock is an unknown quantity. He has not lied to you by omission, because he does not understand the full extent of the situation in which the two of you have become ensnared.”

John tensed. The shrouded threat in Aeserena’s word set his heart beating faster again, ice-like uncertainty entering his blood and coursing through his chest.

“Do not make the mistake of underestimating us,” Aeserena continued, voice lilting and melodious, “for as soft and beautiful as we appear, we are creatures of teeth and claws and dark water, and we hold no sympathy for human men.”

“I know,” John replied, voice low, “I’ve heard the stories.”

“Then let me tell you one of my own,” Aeserena pulled herself further up onto the rock, revealing more of the grey-silver of her tail. Seawater made the surface of her skin slick and gleaming, like silver coins set against the muted grey not unlike the silky-rough flesh of a shark.

“Your human stories are not far from the truth, in how we take our prey. It is easy,” she sighed, dreamily, with a reminiscent smile. “Men are so easily enchanted, are so willing to _believe_ when I sing for them. It is lovely, to feel the moment when they realize I am not coming back to the surface of the water, and neither are they. The struggle is _delicious_.”

John’s stomach rolled, and he fought to keep his face schooled in a mask of polite interest. He had known this, had heard the tales and the claims of danger from Sherlock’s own lips; it was another thing to hear the predator revel in the helpless struggle of its doomed prey.

Aeserena didn’t notice his response - or maybe she did, and didn’t care - and continued to speak. “But the singing and tempting is not a lie; we do want them, just not in the way their human minds imagine. Hunger comes in many forms, after all. It is a matter of misunderstanding, that our appetite is not what they expect -unless it is.”

Her eyes slid to John, and he frowned at her, trying to slot the information together in his brain like a mismatched puzzle. “Are you saying-”

“Where do you think little merlings come from?” Aeserena laughed. “I did say our kind was predominantly female.”

John licked his lips, running his tongue over his teeth in nervous thought. “They don’t survive the encounters, do they? The sailors?” he asked.

The Mer chuckled again, “Oh, no, they do not. But what a way to die,” the smile faded from her lips as her dark eyes narrowed on John again. The bright focus of her stare was eerily familiar in its electrifying effect on John’s skin.  “However… that is not the way it is between you and Sherlock.”

“No?” John said calmly, fighting to keep a composed facade as his stomach clenched and knotted.

“No, there is an older magic at work, as old as the Song, that has diverted your fate. Surely you have felt it,” she lowered her lashes, feigning coy - though without the smile, she looked like a viper preparing to strike.

“Whatever it is,” John spoke quietly, the defensive command in his voice pulled straight from his past, “it’s between me and Sherlock.”

Aeserena grinned, “I will leave you to ask him about it. My son thinks he knows everything; this should be a unique opportunity for him.” The Mer squirmed backwards, sliding back into the fog-covered water with a flash of rippling muscles and glittering scales. She shook out the curtain of salt-crusted curls that trailed down her back, settling them over each shoulder once she was floating in the shallow water.

“So that’s that,” John said, “was that your warning to not break his heart?”

“Please,” Aeserena smirked, eyes narrowed to inhuman slits and sharp teeth gleaming between her plush lips, “if you bring harm upon him I will eat you myself - and I will start with _your_ heart.”

The look that flashed across John’s face must have been a combination of fear and revulsion that made the Mer laugh, and she disappeared into the deep water with her voice still echoing in the moonlit fog.

 

•

 

John was a bit more careful, after that.

Walking into perilous situations - even recklessly so - was in his nature, but there was something cold, inhuman, apathetic about Aeserena that chilled John to remember her. His dreams locked on her: flinty, sharp-edged smiles, the black mercury of her dark eyes, the scars that belied her strength and ferocity. It felt unwise to court such danger, like slipping into dark, shark-riddled water. John supposed the metaphor was more than apt.

It was a tricky balance to strike; John couldn’t – wouldn’t - reveal where he was going or what he was doing on his nightly walks, when they were in port. But it would be stupid to continue his excursions without at least alerting someone that he was not on board the ship. As much as it chafed him to admit, John knew he had to tell someone. Then, if something did happen, his absence would be noticed sooner. John didn’t want to think about the circumstance what would happen, but the pragmatic strategist in him balked at the idea of having no contingency plans, of leaving his crew at the mercy of a true siren should the worst come to pass. But he put it off, again and again, and ducked into the shadows and away from the ship as soon as night fell.

He had yet to see Sherlock again, but the exercise gave him more space to think than the confines of the _Zephyr_ , and the stretch and burn of a long walk felt good on his legs. For the first time in far too long John could start to see his muscles building again, the shape of them more defined under the skin of his calves, his thighs. The warm weight of them, and the confidence they gave his steps, was viscerally satisfying. By the new moon he’d worked himself up to a light, painless jog in the sand each time he escaped to a long stretch of beach.

Tonight they anchored at Taphus, a small port known only for its namesake – the beer hall that served as the island’s inn, meeting place, trading post, tavern. Several smaller ships were docked, fluyts with Dutch tradesmen milling about on-deck, relaxing in the cool afternoon breeze. The midday heat had evaporated the thin layer of clouds clinging to the sky, revealing a bright, untarnished blue that reflected beautifully in the glassy surface of the calm ocean water. As the crew straightened and tied down the shrouds and mainsheet ropes, preparing the ship for port, John leaned over the stern railing to peek at the waves. Taphus’ bright, colorful reefs were amazing to look at even warped and muted with blue from the depth of the water.

John escaped the _Zephyr_ while the sun was still balanced in the sky, dipping lower as the afternoon pressed on. He left his shoes in his cabin; it was easier to jog barefoot, and he knew the sands of this isle were powdery soft and fine. He followed the curve of the shore until the dense canopy of palms enveloped the far shore, the docked ships and squat plaster buildings, masking them from view.  He quickened his pace to a jog.

The island was craggy with coves, and the beach snaked in winding shapes, ribbons of white offset by the turquoise of the clear water. John slowed to a walk when he couldn’t catch his breath, leaning forward to rest his hands on his knees and breathe deeply, achingly aware of the sensations coming from his leg and shoulder: the pleasure-pain of exercise, the burn in his muscles from the activity and the heat on his skin from the sun. He wiped away the clammy film of sweat on his brow and sat heavily in the damp, hard-packed sand at the edge of the surf. The grains of it stuck to him immediately, a pale dusting against his tanned calves and brown breeches, and John shook his head with a sigh, wiggling his toes in the warm slosh of the waves. He’d rest until his heart felt like it was no longer galloping in his chest, and then he’d walk back to the tavern and enjoy the evening ashore.

The sun almost brushed the horizon, now, a deep orange that contrasted with the blue of the sea. The sky was darkening, far overhead, melting from blue to purple to soft pink, blood red, hazy gold in a halo around the sun. Without a cloud in the sky, the sight was enrapturing.

Out of the corner of his eye John saw light reflect off a sudden surge of water, ripples that caught the brightness of the setting sun on the otherwise placid surface of the ocean. His gut clenched; the shape in the waves was dreamlike, but with the glint of scales and shock of dark hair, John knew exactly what – who – it was.

“Sherlock,” John’s lips broke into a small smile, relief flooding his heart – _finally_. “It’s been a while.”

The Mer drew closer as John watched, rapt, parched for the sight of him. He lingered in the shallows, tail brushing the surface of the water, but coming no closer to John than twenty feet.

“Not long,” Sherlock replied mildly, “we did not speak of another meeting during our previous one.”

John raised his eyebrows. “No, we didn’t,” he conceded, eyeing the Mer as discreetly as he could. Sherlock’s shoulders were a tense line above the water, the orange of the sunset spilling over his skin and casting lilac shadows on his neck.

Sherlock didn’t reply, watching John from where he remained, floating half-submerged in the warm water. John pursed his lips; Sherlock’s eyes were too far away to read, but he swam in tight, controlled motions, keeping his distance from the shore.

“I missed you, though, when we stopped at that little island off the southern coast of Hispaniola,” John continued, breaching the silence, “I thought I might see you there.”

“Miss me?” the Mer frowned, perplexed, “Why would you miss me? Thus far our meetings have been, on average, more than one week apart – and not necessarily every time your ship reaches land, so why would- ”

Sherlock stopped when he noticed that John’s grin had grown broader, his arms crossed over his chest.

“No, no, go on,” John chuckled, waving for Sherlock to continue, “deduce it. Tell me why I would miss you.”

 John swallowed but continued to smile when, in an instant, Sherlock’s intense focus was centered on him. Heat bloomed in his blood as the Mer’s gaze traveled along his skin, shoulders and arms to hands, his bare feet and exposed calves, twice-patched breeches, sweat-damp hair. John had to remind himself to breathe.

“When you say you miss me,” Sherlock began, “You mean that you have noticed – or, rather, _felt_ – the effects of a prolonged absence between us. Typically, the longer the absence the more keenly it is felt.”

He paused, narrowing his eyes, “It is natural to form habits over time; patterns in the occurrences of daily life are comforting, familiar. Routines are an anchor in the chaos of circumstance. However, we have not met enough times to truly form a habit. No, for you to miss me, you must…”

John raised his eyebrows when Sherlock trailed off. The Mer blinked away the frown forming on his face, his expression caught somewhere among tentative, nervous, and confused.

“For you to miss me, you must be thinking of me, and often. It suggests a stronger sentiment than that between acquaintances.”

“Well,” John cleared his throat of the sudden roughness in his voice – Sherlock’s rapid-fire deductions were thrilling and undeniably attractive in the Mer’s baritone. He tipped his knees inwards as subtly as he could, hoping Sherlock was too far to observe the effect his voice had had.

“In my defense,” John said, “There’s really not a lot to think about out here besides the ocean. And you’re-”

He waved a hand in Sherlock’s direction, and Sherlock’s confusion morphed to wry amusement.

“How flattering,” he drawled, brushing his curls away from his face, “and specific. You’ve gestured to all of me.”

“All of you _is_ interesting,” John smiled, leaning forward to rest his elbows on his knees, “even more now that I can see you properly. I haven’t ever seen you in the sunlight before.”

“The night is safer,” Sherlock nodded, mouth pressed into a thin line, “The dark and the deep are the best places to hide. It has been easier for you to get away unmissed in the midnight hours as well.”

John hummed, “That’s true. You’ve come to me now, though.”

“The sun is setting soon.” The Mer glanced over his shoulder at the gold-flecked water, and the outline of his hair caught the fiery shades of the sun in bright yellows and oranges. “We are far enough from anyone else that it should be safe.”

“Are we?” John didn’t know how far he had run, how far back the _Zephyr_ and her crew were – but Sherlock did, and thought it was safe enough to appear before him in the warm, waning light.

With a sharp inhale John surged to his feet, wiping the sand off the back of his breeches as best he could with his palms. It did little to help where the sand was damp enough to stick, but it would have to do. He took a step forward, into the ankle-deep water.

“Don’t!” Sherlock’s voice rang out clear across the water, despite the roar and murmur and crash of the surf against the sand.

“Don’t what?” John asked, bending at the waist to roll up the dragging hems of his breeches. They were already powdered with the fine, white-pink sand under his toes, but there was no sense in getting them soaked through if he didn’t have to. He folded and rolled them into cuffs at his knees, then stepped into the warm, foamy rush of water.

“Don’t - do not come any closer!” With a faint splash Sherlock moved deeper, retreating further for every step John took to close the distance between them. When he was knee-deep in the surf, John looked down, considering, and shrugged. He continued wading into the ocean, stirring up the sand at the bottom as he sloshed forwards. The water quickly wicked up the cloth of his breeches, pressing them to his legs like a second skin. Sherlock stared.

“I’m not going to hurt you,,” John called, milling his arms to keep his balance in the murky sand, moving thickly through the water as it got deeper and deeper. “Just - come here. I haven’t given you any reason to be afraid of me, I think; on all accounts, this should be a spectacularly bad idea on _my_ part, but not a risk at all for you.”

Sherlock’s ears flattened against his head and he narrowed his eyes. “The fact that you comprehend _that_ much and refuse to see the blatant danger in us approaching one other is evidence _against_ your supposed intelligence,” Sherlock sneered, but John only grinned - the veneer of bravado and annoyance that Sherlock was putting on was a mask for his uncertainty, which John could see lingering in his eyes.

“Oh - insults, my favorite form of flattery. Look, we have an agreement; I’m not going to try to capture you, and you’re not going to eat me. I just want to get a closer look at you. It’s a good opportunity – it’s safe. I’m curious.” John stopped moving forward, watching as Sherlock’s tail beat under the clear waves to keep him floating in place only yards away. The Mer was staring at him, warily, his muscles tensed and poised as if expecting John to lunge for him.

John sighed, holding up his hands with his palms towards Sherlock in a placating gesture. “I’m not going to push you, Sherlock. Why don’t you come closer, and I’ll stay here? I promise I won’t move or touch you.”

Sherlock quirked an eyebrow, and John quickly amended, “Unless you want me to.”

A blush rose on the Mer’s cheekbones, no doubt at the memory of the first and only time they had made contact, on the night of the full moon already many days past. The sense-memory still left John’s lips tingling, and he was suddenly thankful that he had waded in up to his waist.

“Is this deep enough for you to get closer?” John asked, gesturing to the waves around him. The water came nearly all the way up to his navel, so his shirt was beginning to soak, too. The air and sea were mild, though, and with the soft warmth of the setting sun on his skin, John didn’t feel cold at all.

“Yes,” Sherlock admitted, face pinched in annoyance at conceding the point, and John tried to keep his breathing steady and reign in the delighted grin on his face as Sherlock slowly, cautiously, swam forward.

Oh, he was gorgeous. The crystal-clear water afforded John a sight that had been impossible in the dark: a full view of Sherlock’s lower half, the silvery tail that propelled him forward with every sinuous beat. It was a warm silver, nearly champagne-pink in places, where his skin faded from pale and human to the bright disks of scales. His tail was only a little longer than what John imagined human legs would be, if Sherlock had had those instead; it tapered, all lean, smooth muscle, into a broad, thick fin not unlike that of a dolphin. A thin, translucent ruffle of webbed skin lined the outer edge of the fin, trailing and fluttering with every movement Sherlock made. He was incredibly graceful, moving naturally through the water, and John watched the muscles in Sherlock’s torso and arms stretch and bunch as he swam languidly closer.

“Incredible,” John breathed, aching even more to touch and discover the texture of the Mer’s skin. Would it be slick to the touch? What would it feel like, under his fingers, where flesh turned to scale? He wanted to catalogue the differences in muscle structure and the ridges of Sherlock’s spine, how the Mer’s body was built so human-like and yet so perfectly designed for fluid movement through the water. Curiosity and the human craving for contact warred against John’s restraint at the uninhibited sight of Sherlock.

The Mer approached until he was just out of John’s reach, treading water so that half of his chest was above the surf. John spread his fingers and let them drag through the water around him as he swam, wishing he could be tangling them in Sherlock’s dark, dense curls instead.

“Well?” Sherlock asked, hovering in the water gently. Despite his bored tone, John could sense the tension rolling off Sherlock in waves.

He quirked an eyebrow. “Fishing for more compliments?” John grinned at his own joke, an attempt at diffusing the tension between them as he let his eyes run up and down Sherlock’s body more overtly. “You are a marvel. What is your flexibility like?”

“Much like yours, I imagine, in my upper body and arms,” Sherlock replied, swimming a lazy circle around John, “our musculature there appears to be almost identical. Take off your clothes.”  

“Sherlock!” John garbled in surprise, blood rushing to his face. The Mer smirked.

“Have I offended your human sensibilities? Humans often go without their shirts in the company of others; it should not be an unusual request. I want to look at your skin. You are in the water, besides; your clothes could not get any more wet than they already are.”

John turned his head to follow Sherlock as the Mer swam around him, circling him calmly and observing John from every angle. Was Sherlock - _flirting_? John’s blood surged at the thought; surely Sherlock was only curious as well, the closest to a human being that he’d ever been, and wanted to absorb as much as he could with this opportunity to observe. Despite the surprise of John coming so close, Sherlock had warmed to the idea quite quickly, and John attributed it to his natural thirst for knowledge. But perhaps…?

“Just the shirt,” John pretended to grumble, plucking at the ties of his shirt and clawing the soaked linen over his head. He dropped it into the water next to him, where it floated near the surface, waterlogged and nearly translucent.

Sherlock didn’t even glance at the discarded cloth, his eyes locking on the radiating starburst of scar tissue at John’s shoulder. John set his jaw, tensing at the attention - he’d nearly forgotten about it, the tepid water and warm sun dispelling any ache in his shoulder that came with the cool air of night or the physical work of a doctor. The Mer was entranced, drawing closer to John to examine the old wound at different angles. He fluttered like an interested, if uncertain butterfly, looking for a place for his fingers to alight on John’s skin.

“May I touch you?” Sherlock murmured, voice deep and eyes lit with an intense  fascination that John had only gotten a glimpse of on the first night of their acquaintance. His eyes flicked up to John’s, waiting and watching, though his hand had started to extend towards John’s chest as if by its own volition.

John cleared his throat. “Yes,” he said, voice soft. Sherlock stared at him a moment longer, reading his expression, before reaching out to put his fingertips at the edge of the silvery scar, below the line of John’s right clavicle.

His fingers were wet and slightly cool, a contrast in temperature to John’s tanned, sun-warmed skin. Fat drops of water skittered down John’s chest, which felt all the more sensitive with an inquisitive Sherlock front-and-center in his personal space. Sherlock leaned in, tracing the spidery edges of the scar, chasing the differences in texture between the old flesh and the new. His breath steamed John’s skin, and John felt Sherlock’s sharp inhale when he pressed against the scar, dipping into the divot left in his shoulder where a ragged hole had once been.

“What makes this kind of wound?” Sherlock asked, meeting John’s eyes. “Is it sensitive?”

“A gun,” John said, “a bullet. And no, the skin itself isn’t as sensitive as it used to be. The scar tissue is dense, doesn’t allow me to move my shoulder in the same way anymore. I can’t feel sensation as clearly as I did before – it’s dulled, though I can feel it. The scar is more sensitive to cold and bad weather.”

Sherlock nodded, mostly to himself, and continued to prod at John’s scar. It wrapped around from the front of his shoulder, nearly where the cap of his deltoid muscle met his clavicle, to the back, where an imperfect circle of tissue showed the bullet’s entry. John knew his shoulder was a mess, knotted and scarred and littered with stretch- and pock-marks, far from glamorous or attractive.

“I was right,” Sherlock muttered, now-dry fingers tracing up and down the scar in what was almost a caress. “New injury, no more than a year and a half since it was inflicted. You were pierced from behind, and the bullet almost exited your shoulder on the other side - not quite, not enough to leave a clean wound. You had to dig it out yourself.” Sherlock’s eyebrows were drawn together in a small frown, but the gleam in his eye almost looked approving as he continued to trace over the pale scar.

John caught Sherlock’s elbow, stilling the movement of his hand. “You _are_ right,” John agreed, “But, um - I won’t lie to you about it, but I _would_ rather leave it in the past.”

Sherlock pursed his lips, nodding tightly, and the ball of nerves knotting in John’s chest unwound. He knew it couldn’t have been easy for Sherlock, to reign in his natural curiosity, but he’d done it for John’s sake. The thought made him a little light-headed and he stared at the Mer, unguarded.

“Your turn,” Sherlock said, pulling out of John’s gentle grip.

“My turn?”

“Yes, do keep up,” Sherlock rolled his eyes, “That is how we formed our friendship in the first place, is it not? I touched, now you can.”

John gulped. The idea of it, to finally give into temptation - run his fingers across the Mer’s skin, or through his hair, sensations he’d imagined for week after week, nearly from the first moment they’d met – it sent a spark of arousal down his spine. He willed his face to not redden, hoping he could blame the color on the pinkening sky and its reflection on the gently rolling water.

“Are you ticklish at all?” The words were out of his mouth before he could think on them, and Sherlock narrowed his eyes.

“Ticklish?”

“Sensitive to the touch anywhere in particular?” John clarified, reaching out slowly with his left hand towards Sherlock’s bare hip.

“I do not think so,” Sherlock said, but his words were hesitant, his tone nervous.

“Not going to hurt you,” John repeated, speaking quietly. Sherlock was understandably skittish, but had offered willingly, which made John’s heart thrum and his pulse quicken.

The third touch was not quite electric like the first, or as contrasting in temperature like the second had been. Underwater, Sherlock was warm and the ridge of his pelvis a solid arch, smooth under a layer of light skin and muscle. Here, his flesh felt human, and John lightly skimmed his fingers lower to where the color and texture began to change. The tiny, bright scales that dotted Sherlock’s skin were smooth, but not hard like nail or bone, and as they grew larger John could feel the miniscule ridges where they slotted together like seamless tiles. Up so close, he could see that the pink tinge of these first scales was from blood vessels weaving together under Sherlock’s skin. Experimentally, he ran his hand further down, to where the scales were almost the size of silver pence, down Sherlock’s flank. The dense, corded muscle under the surface of scales shuddered into his palm, and a bitten-off gasp made John raise his eyes in an instant.

“Too much?” he asked, moving his hand back up to more familiar - human - territory. Sherlock looked abashed at his reaction, tail flicking underneath the water in annoyance and nervous energy.

“No,” the Mer said, voice wavering slightly. John pretended not to notice. “Continue, if you wish.”

John held his gaze for a moment before looking down, focusing again on Sherlock’s tail. It wasn’t slimy but clean and a little slippery; his hand slid down Sherlock’s flank again with gentle ease. He kept the contact light enough for Sherlock to pull away, if he wanted, but firm enough for the Mer to know where his hands were, to feel the warm weight of his fingers and palm. He mapped the groups of muscle, pressing gently at the interlacing ridges of flesh underneath the scales, scanning for scars or marks of infection - but Sherlock kept his tail immaculate. John had a feeling that _unmarked_ didn’t mean _out of trouble_ , in Sherlock’s case; his curiosity about humans led to a lot of risk-taking.

Sherlock’s tail bent and flexed under his touch, muscles pulling taught and contracting again in slow, controlled movement to keep him floating in the water. John was fascinated.

“How does it feel?” the Mer asked, and John looked up. Sherlock was watching him with a gentle, amused expression on his face, though the high color in his cheek betrayed the effect John’s touch had on him.

“I’ve handled fish before,” John said, tugging at Sherlock’s hip to draw him closer, intending to look at the fin-like ears tucked into his curls.

“Fish?” Sherlock snapped, bristling, “I am no _fish_ , John. It is vulgar for you to suggest-”

 “Sorry! Sorry,” John said, stroking the smooth scales, “I just meant – you don’t disgust me, in any way. It’s – _you’re_ \- amazing. There’s a certain beauty in the marriage of form and function. Anyone can appreciate that, not just a doctor.”

Sherlock preened, fairly glowing under the attention. He didn’t startle when John brought up his other hand, thumb tracing Sherlock’s jaw before tilting his head to examine his ear. John brushed away a few curls, a little crisp with salt now that they were drying, and he tried not to shudder - they were as soft as they looked.

John had been right in his estimate that Sherlock’s ears were mostly human-shaped but frilled with thin pink skin and delicate fins. The whorls of his ear fanned out into gentle points, connected with elastic, translucent tissue  spanning from pink to pale silvery-blue, like the scales on his tail.

“How can you stand it?” Sherlock asked, tipping his head to dislodge John’s hand and meeting his eyes with an open, curious expression.

“Stand what?”

Sherlock waved a hand at John’s lower half, “Being so - _divided_.”

John laughed, not expecting the simple question and the word that Sherlock had packed full of confusion. He looked down the length of his body and into the water at his toes, now partly submerged in the cool sand. He wiggled them, the sand so thin and fine that it rustled in the water and formed a foggy cloud around his feet.

“I don’t know,” he said, “I’ve always had two legs, and can’t imagine anything different. I suppose it’s rather like having two arms.”

Sherlock scrunched up his nose as John’s answer, as if he found it unpalatable. “But how does it work?” He ducked out of John’s grip to circle around him again, flitting closer and tugging at the waist of John’s breeches with deft fingers. “What is it like, where you _separate_?”

John sloshed through the water as he took a haphazard step backwards, away from the Mer’s prying fingers. “Sherlock!” he spluttered, “That’s - um - you’ve never seen a human naked before?”

“No,” he replied bluntly, gliding through the water towards John with a natural, seductive grace, “I never thought to, never _wanted_ to before.”

“But surely you’ve - when you’ve hunted -”

“If I am truly hunting and in need of sustenance, then I am not of mind to be exploring the intricacies of human anatomy. Now, however-”

Sherlock continued to advance towards him until John was only thigh-deep in the shallow water, cloudy with sand from his frantic movement. A misstep made John’s leg twinge and he staggered onto one knee, bringing him to Sherlock’s height with a lurch and a splash. John blinked the water out of his eyes, breathing heavily through his nose, to find Sherlock creeping closer with a wary but determined expression.

He swam into John’s space, staring unflinchingly at John until they nearly pressed flush chest-to-chest. John’s blood sparked cold and then hot, the nervous tightening and excitement in his gut building. Sherlock’s hands settled on his hips, pulling John down further so that he was kneeling in the shallows, looking up into Sherlock’s face.

“Sherlock,” John murmured, voice husky, “what are we doing?”

The Mer watched him from half-lidded eyes, fingertips tracing ghostly paths up and down John’s skin, sweeping up towards his ribs and down again, to the crest of bone at his hip. This close John could smell him, a faintly human scent overlaid with sandalwood and a deep musk, clean water and bright salt.

“Why did you run?” John asked when it was clear that no other response was forthcoming.

“Why did you kiss me?” Sherlock replied, eyes flashing. John ducked his head, watching the bunch and flex of tendons under his own skin as he clenched and unclenched his fingers. He licked his lips; he didn’t have a proper answer.

“John.”

The use of his name sent a jolt through John, and he met Sherlock’s eyes. The sunset was fading, orange to pink to purple and blue, the brightest of stars beginning to appear overhead. The edges of the wispy, cotton-thread clouds were still laced with gold-orange, but besides their bright silhouettes they were nearly indistinguishable from the twilit sky.

It took conscious effort to stop himself from fidgeting or looking away; John owed that to Sherlock, at least. He took a breath and exhaled in a steady stream. The truth.

“I - don’t know,” he said, “it felt like the right thing to do, at the time. You amaze me. And - I wanted you to believe that.”

Of its own accord, John’s left hand began to stretch through the water, breaking the surface and dripping as it neared the Mer’s shoulder. Sherlock caught the hand reaching between them, easily encircling John’s wrist with two long fingers and thumb. John felt the blood under his skin with a heightened sensitivity, like the pressure Sherlock put there was only just stoppering it from pouring out of his veins.

“Amazing,” Sherlock repeated, “Brilliant. Fascinating. You do know that you do that out loud?”

“Sorry, sorry,” John flushed, shaking his head, “I’ll - I’ll stop.”

The Mer pursed his lips. “No,” he said. “It’s...fine.” His thick brows pulled into a frown, and his eyes fell to their connected hands. Slowly, as if moving through honey, Sherlock ran his thumb up the sensitive inside of John’s wrist, so pale against the freckle-dusted gold of John’s tanned skin.

“I know I repeat myself,” John said quietly, mostly to Sherlock’s clavicle - though he could see the moment the Mer looked up, bright eyes boring into him, “about how amazing I find you, how stunning and incredible you are to me. I just - I never thought I’d get a life like this, after - well, after everything that happened. There kind of - stopped being colors, do you know? I never cared about the sea. I wasn’t in love with it.

“And then you appeared out of the deep, out of the blue in the night - I almost thought you were a dream. But there was the second time, and then-” he sucked in a breath “-well, I felt something, when I walked away.”

“Primarily anger, if I recall,” Sherlock rejoined, eyebrow arched but tone flat with dry wit.

John chuckled, “Well, yes. But anger, and fear at the beginning - in two hours of your company I’d felt more than I had in the four months previous.”

Sherlock considered this, tail flicking about in the water as he thought and sending whirling ripples to the surface. John rocked back on his heels when a particularly strong current from a wave pulled him backwards, but Sherlock’s hand on his anchored him, and he rocked forward again, in balance.

“You needed danger,” the Mer said finally, tipping his chin down to stare into John’s eyes, as if confirming his words with what he found there, “to feel alive?”

John’s gaze was drawn to Sherlock’s lips as he leaned forward, and he quickly pulled them back up - but the Mer had undoubtedly noticed. Sherlock noticed everything.

“Yes,” John replied, his voice deep and hoarse to his own ears, “I guess I do.”

“I am not sure there has been quite enough of that tonight, John,” Sherlock hummed, and John saw the Sherlock’s pupils dilate and felt the rush of warm breath across the skin of his cheek.

“It’s only just become night,” John said, “but we can amend the lack of danger, I’m sure.” He let a slow smile stretch over his features, intentionally glancing at Sherlock’s lips now, licking his own in an obvious display of -

Sherlock was kissing him, had surged forward like a coiled spring to press, finally, fully against John. He was heavier than he looked, all dense, corded muscle and sinew and scale, a warm weight under the cooling layer of water that still clung to his skin. John wrapped an arm around him, drawing them closer together, grasping at the small of Sherlock’s back and tracing the dimples at the base of his spine. Sherlock made a surprised, pleased noise in the back of this throat, coaxing John’s lips to deepen the kiss. John couldn’t help but kiss back, the heady sensation of Sherlock’s mouth against his making his blood rush and his fingers wander, unable to keep still or stop touching.

Sherlock cupped John’s jaw with both hands, tilting gently until they were even more perfectly in place, sliding against one another in a seamless push-and-pull. John licked at Sherlock’s bottom lip, at the corner of his mouth, at the perfect cupid’s bow until Sherlock’s mouth opened under his, and he coaxed the Mer’s tongue with his own. John probed gently, softly, careful of the pointed canines and curled his tongue around Sherlock’s. His mouth was hot and slick, and Sherlock was a fast learner; he was pliant at first, but grew in boldness until he was chasing John’s tongue, experimentally biting at John’s lips, which earned him a graveley groan.

Feather-light touches at his knees and the tops of his thighs made John’s skin prickle; Sherlock’s fin grazed his legs with every movement as he pressed against John and made small rocking movements. John could feel himself hardening in his breeches, which already plastered to his body from the water and left little to the imagination. His breath hitched when Sherlock rocked against him, hard, movement like an incoming tide, in inches but inevitable.

Sherlock’s attention moved from John’s mouth to his jaw, to the soft crease between bone and ear. John gave a full-body shudder, scrabbling hard at Sherlock’s shoulders and threading a hand into his hair. The Mer hummed, nibbling the lobe of John’s ear and licking at the sensitive whorl of tissue.

“Sherlock,” John groaned, unable to resist grinding them together. A hardness echoing his own nudged against his thigh, but before John could think on it, Sherlock gave a mighty pump of his tail and knocked them backwards, towards the shore. John landed with a muffled splash, blinking away sand and surprise. They lay at the edge of the surf, the gentle waves lapping around them unhurriedly. John’s legs had fallen open when Sherlock tipped them off balance, and the Mer lay on top of John between them, hands on John’s chest and panting hard, glancing down to where they were pressed together from chest to mid-thigh.

“John,” Sherlock purred, giving him a smug smile that lit up his features, and John couldn’t help but find himself grinning back. He used the hand at the nape of Sherlock’s neck, tangled in his wild curls, to pull him down for another kiss; it started as heated as before but John slowed it, tamed it until their tongues were languid and caressing and deeply sensual in their movement.

They kissed for what felt like hours, ‘til all of the pink and orange had long drained from the sky to leave it midnight-dark and pregnant with thousands of stars. Only then did Sherlock rise on his elbows, out of John’s embrace; his eyes were pearl-pale but softer than John had ever seen them. He wriggled backwards, through the water too shallow to swim, until his tail fanned out properly and he could ease back into the calm waves. He held out a hand to John, who was still reclined and pliant in the sand. The tide had started to come in, the water deeper around John’s reclined body, and he felt cool in the absence of Sherlock’s skin against his. Sherlock raised an eyebrow when John just watched him with an amused but fond expression. John’s shoulder twinged when he sat upright, but he followed Sherlock back into the surf.

Sherlock was exploratory and gentle in rinsing the sand from John’s bare skin, brushing away the grains that stuck in his breeches, in the fair hair on his arms, the nape of his neck. His fingers swept proficiently, but lingered here and there - John wasn’t sure the Mer knew even he was doing so. But all too soon John was clean, and Sherlock recovered his missing shirt, which hadn’t floated far in the gentle waves. He pressed the soaked linen into John’s hands, meeting his eyes with a small smile.

“Go back to your ship, John,” Sherlock said, reluctantly pulling his hands away.

“Will I see you again?” John asked, an honest, open grin betraying that he already knew the answer.

“Yes,” Sherlock replied, facing John but drifting away into deeper water. “I am sure we will see one another soon.”

John felt a little like a schoolboy with a crush, cheeks aching from his smile. “Yes, well. Good.”

They stared at each other a little longer, the tide rushing around them. John sighed, smiling and shaking his head at himself, before turning and slogging through the waves to the dark shore.

“By the way,” John called, turning to see that Sherlock had stayed where he was, watching John’s retreating form. His eyes snapped up to John’s face from somewhere near his waist and John’s stomach flipped. “Did you do anything strange to my compass?”

“Your compass?”

“Yeah,” John  sighed at the feeling of sand working between his toes again, “When I gave it to you to keep safe for a week. Did you do anything to it? Or did something happen? It doesn’t point North anymore.”

Sherlock pressed his lips together in a hard line, a frown creasing his brows. “No,” he said, “I do not believe-”

The Mer cut himself off mid-sentence, jaw clicking closed as he looked down and to the side, his tail twitching in agitated motion under the water. John could almost see his mind flipping through the days of that week, seeking any anomaly or hint at what could cause such a bizarre thing.

“It’s fine, Sherlock,” John said, “really, it is. I don’t think it’s broken, exactly. You didn’t bring it any harm, and from the look on your face I know it wasn’t intentional.”

“Maybe not intentional,” Sherlock said after a long pause, “But - I will see what can be done. Bring your compass with you, next time.”

“Next time,” John repeated, heat rising to his face. Sherlock’s pale eyes gleamed at him until he turned away again, heading for the line of trees that separated the shore and the hilly dunes beyond. He felt Sherlock’s gaze, like a comforting weight, until he was sure that the land had swallowed him from Sherlock’s view.

  
•

 

“Tell me, Doctor John Watson,” Stamford called to John as he climbed the worn gangplank up to the deck of the _Zephyr_ , “where do you go when you get shore-time that does that to you?”

“Does what?” John asked, thankful that the half-darkness hid the flush on his face. Had the Mer left a mark somewhere on his neck? He resisted the urge to rub at his skin, sure that the motion would give away some part of his hefty, precious secret.

But Stamford was well-meaning, soft in belly but sharp in mind and one of the most perceptive members of the frigate’s crew. John had already learned that from the pointed – and often correct – council the man gave. “You took my advice in Port Royal, I assume. To take a walk about the town, or at least to get off the _Zephyr_ for a couple hours. Now, you look completely refreshed after you’ve spent your few hours ashore, whenever we make berth. Doesn’t matter the port, or if  it’s night by the time we arrive - or maybe _because_ it’s night?” Mike waggled his eyebrows a little, and John laughed. He swung his knapsack off of his shoulder and started for the stairs down to the lower decks, Stamford trailing behind him.

“No, nothing like that,” John said, the lie fluid on his tongue even as a cool trickle of sweat wound down his back and his heart tripped in his chest - _someone had noticed_. It had been Stamford, perhaps one of the most good-natured of the _Zephyr_ ’s crew, and one of the first to warm to John when he joined - but still. It pricked at the edges of John’s mind, cold and bright, a reminder that his actions didn’t go unnoticed. John pressed his lips into a thin line; he would have to be doubly careful with his comings and goings in the future.

“Come on,” Stamford urged, grinning, “Won’t share? Trade secret, then? I’d almost say you’d found a girl to bed, but-”

“But?” John turned sharply on his heel, executing a perfect, military turn, and Stamford had to stop short before they collided face-to-face.

The ship’s cook had an easy, unassuming smile on his face, “But,” he said, “That wouldn’t explain how relaxed you look on board, too. Unless she’s _that_ good of a shag.”

“Yes, well,” John said, clearing his throat and trying to keep the rising smile off his face.

“Whatever it is,” Stamford clapped a meaty hand on John’s shoulder, using it to pivot and step around the doctor, making his way into the shared crew’s common area, “I’m glad for you, John. I’m no medical man, but your limp’s all but gone, and you’ve been eating better - so whatever you’ve found, hold onto it.” John watched Stamford shuffle to the galley, already chattering cheerfully with Donnie and Gregson. John shook his head and turned, continuing down the narrow corridor with his mind whirling.

In his own tiny cabin, John slipped off his sand-filled shoes and attempted  to remove the grit from his feet, turning Stamford’s words over and over in his head. The _Zephyr_ didn’t have an overly-large crew, but she was a privateering vessel, and they all knew each other on sight, from above or behind, in darkness as well as the bright noon sun. It was only a matter of time before someone noticed his regular sojourns on shore – and not in the friendly, curious way of Stamford. It wasn’t against John’s duties in any way, nothing he could get in trouble for - but it did mean he would have to be cautious. He couldn’t let anyone follow him; Sherlock’s existence was a secret he promised he’d keep safe, if not in words then in actions.

 _And_ , a deep recess of his mind whispered, _you want to keep him for yourself._


	5. Chapter 5

**Summary for the Chapter:**

> "Bollocks to what is safe, Sherlock," he whispered, "What do you want from me?"

**Notes for the Chapter:**

> Here is chapter five of 'and the sea so deep'! Thank you so much for your wonderful comments, words of encouragement, and patience. The chapter is a monster, coming in at over 16,000 words - that's more than the first two chapters combined! So please enjoy, quite a lot of work has been put into getting it where it is!
> 
> My undying love to [Meg](http://forsciencejohn.tumblr.com) and [Ruth](http://youseebutdontobserve.tumblr.com), who read this for me several times and put up with my whining; especially Meg, who has helped get this story back on track in ways you've yet to see. For [Michi](http://traumachu.tumblr.com), too, who is always a writing inspiration and enabler in the best of ways. Thank you!
> 
> A further notice - the rating of this fic has changed from M to E; this is one of the chapters in which E happens. Enjoy!
> 
> For fic progress updates and writing snippits, you can find me on tumblr as [venvephe](http://venvephe.tumblr.com/), where I update quite frequently with my current projects.

 

The quarter-moon that hung over Jamaica was strangely foreboding; it was a circle neatly sliced in half, and to John it looked severed, barren and cold. He felt he had to be thankful to the moon, but its presence seemed a wary eye on his back that night. The sky was inky, thick blue-black in comparison to the moon, with grey needlepoint stars that matched the humid haze clinging to the horizon.

“Oy, John,” Murray’s footsteps were light across the mid-deck as the sailor came to John’s side, fairly bouncing on his heels with happiness. “It’s been a while since you came with us to a pub ashore - a man needs his solitude, but surely you can give up your lonely walks for one night to join us for a pint?” He clapped John on the arm, good-naturedly, and John found himself smiling in return.

“I think I can do that,” he replied, taking Murray’s hand off his shoulder to examine it. The oily yellow light spilling from the lantern hung on the main mast was dim, but from the texture of Murray’s palm under his fingers, John could tell that the injury was healing nicely. “Have you had any problems with it? Stiffness? Soreness?”

“You did a right good job, Doc,” Murray shook his head, “None and none, I’m happy to report. Keepin’ it wrapped the first week wasn’t easy for the rope work, but it feels fine!”

“I’ll look at it again in better lighting,” John nodded, letting Murray’s hand slip from his grasp, “but if it’s been kept clean and it has healed well, I expect you won’t have any more problems with it.”

“Besides an impressive scar,” Murray waggled his eyebrows, and John laughed.

“I’ll let you tell everyone you got it in a fight with a pirate.”

They waited for a few more members of the crew to gather in their little pool of light before clambering down the gangplank and into the town. They made a merry band of sailors, welcoming the feel of hard land under their feet and looking forward to the twin comforts of warm food and good drink. John was jostled and elbowed and teased with the rest of them, their boisterous laughter loose in the night air instead of trapped in the crew’s shared mess in the belly of the _Zephyr_. It was warm and comfortable and John relaxed, but the tense set of his shoulders never slipped off completely. He glanced at the stars, knowing they would be there when he had finished at the pub, knowing Sherlock would be waiting for him. His stomach flipped.

The buzz of anticipation lingered in his veins, fizzing like the bubbles that popped and foamed in the tankard of ale that was plunked in front of him in the bustling tavern. The metal was slightly cool against his fingertips, and John wiped the foamy liquid from the sides of the tankard before gripping it and bringing it to his mouth. The ale was bitter and yeasty on his tongue a much better brew than they’d had for the last two day on the _Zephyr_ , draining the dregs from one of the kegs by mixing it with water to form a thin, tasteless grog.

“That’s the stuff,” Stamford sighed, setting down his ale and wiping the foam from his upper lip with a satisfied smile, “Nothing beats that after four days of the piss we’ve been drinking.”

“Could’ve cracked the next keg, but then we’d be high and dry for the rest of the way down to the Indies,” Gregson raised his eyebrows, draining his drink and smacking his lips, “and then where would we be, eh? With no stories to tell and no drink - we’d rot below-decks before we got all the way south.”

“Doctor Watson wouldn’t let us,” Stamford toasted John with his pint, and Murray thumped him on the back again; they did seem to get rather physical when they were on land, despite rubbing shoulders in the confines of the ship almost every day.

“Ta, though I won’t deny it’s crossed my mind a few times, with the way you lads complain,” John said to a round of laughter, “and we’ll have both stories and ale tonight, now that we’ve got something firm under our feet.”

The sailors toasted again to that, laughing when they got too boisterous and the table became sticky with running ale. John could feel his cheeks turning pink, pinched from so much smiling - he had missed this, really. Much of the time he spent aboard was in solitude; when things went well, there was no immediate need for the ship’s doctor. Thoughts of Sherlock ran through his head, when there was little else to do, and John was conscious of every expression that crossed his face.  It was easy to write off as daydreaming about some girl, but once too often and his shipmates would become more curious, ask for more details - it didn’t help that Stamford had already cottoned on to the growing changes in John.

“How about it, then?” Murray asks, looking imploringly between the gathered crewmates, from one to another, “A story or two? Been a bloody while since Doc’s had a go at sharing-”

“Yes, tell us,” Gregson pressed, grinning from ear to ear, “I’ve heard all the tales that these bastards have to offer - tell us a new ‘un.”

John glanced around the circle of faces, unease welling in his gut to replace the warm weight of relaxation. He was among friends, he knew that, but he still had a prickling, cool feeling at the nape of his neck of being watched. He’d scanned the room when he entered, old military habit - he knew where the doors and windows were, knew that his crew was the largest group in the pub tonight, knew that the other patrons were locals and merchants and of little danger to any of them. He couldn’t put his finger on it, though, and John flexed his fingers on his thighs, pressing his lips together in indecision. To tell a tale, or not? And what yarn to weave?

They looked to John with eager anticipation, and even with the unsettled nerves at the back of his mind, John couldn’t help but find it flattering that they want to hear him spin a tale. He had always fancied himself a decent storyteller. He wiped his palms on his breeches, curbing his restlessness and smoothing the marks his tight grip had made.

“What-” he cleared his throat, “what kind of story do you want to hear?”

The sdden clamor of voices drowned out any one response, and John waved them down to point at Murray.

“Ghosts,” Murray replied instantly, rubbing his hands together.

“Girls,” Gregson raised his tankard, to a murmur of assent around the crowded table.

“Right, well,” John said, smiling, “we’ll have a bit of both then.”

John made a bit of a show of adjusting his rolled up sleeves and clearing his throat, taking a sip of ale and making eye contact with each of his rapt listeners before he launched into his tale. The background noise of the pub faded away, the clinking of glasses and tankards and murmur of voices lost as John saw the story forming in his mind’s eye, feeling the words form and his lips tingle with the anticipation. There was a certain thrill in telling a captivating story, and John was flirting with danger with the tale he was about to tell.

John licked his lips and put on a small, conspiratorial smile as he settled in to start. “Well. You know a week ago, when we had that really foggy night - so foggy you couldn’t tell one foot from the other, like we were sailing through a cloud?”

It was just a taste, a hook to draw them into the story. It was enough, it worked; the tankards of ale were set to rest on the sticky table as the sailors’ attention locked onto him. John scooted his stool forward, leaning over the table to speak to his companions quietly, weaving the air of mystery around his words.

And then John spoke.

He told them of the sighs he had heard, coming from the opaque, dream-like fog that had settled around the ship, of a voice that sang to him in long, trembling syllables – whispering for him to come to the shores and to put his feet where the land met the sea. He told them of the stillness of the water when he had done so, of the unnatural quiet like that which preceded a thunderstorm, and had shrouded the beach from the outside world. He told them of the crush of sand underneath his feet, cold for the Caribbean, and the melody that haunted him from out of the mist until he stepped into the water itself.

“And then,” he said, when the group was hanging off each word, entranced, “ she appeared.”

“What did she-”

“Shh!” Gregson was immediately shushed for interrupting by the rest, and he pouted, thoroughly chastised for breaking the flow of John’s story. John smiled at him, mollified, and Gregson motioned with his tankard for John to continue.

John indulged them. “She was fair - so fair and pale, nothing like us blokes who get roasted by the sun all day and turn dark as a chestnut. But her hair was dark and curling, gleaming like it was cut from black glass. It fell all the way to her waist - and that’s when I noticed that she wasn’t human.”

A collective ripple passed through his listeners: the tightening of fingers around a mug handle, a sharp intake of breath, the shuffling of feet under the table.

“She was a Mer - but not just any Mer; she was their queen,” John said, “and her tail was brilliant - like silver coins hammered into cloth and wrapped around her strong, curved body.”

“How could you tell she was the queen?” Stamford asked, awed.

“She told me,” John said, “and she wore long strands of beautiful, perfect pearls that dangled all the way down her body from her neck. When she came out of the water she perched on a rock, dripping with water and foam, her skin shining silver in the moonlight. She was clean and so pale, except for her bright pink lips and her cheeks; lean with lovely curves for her hips and oh, her breasts,” John raised his eyebrows and the men chuckled, filling in the rest for themselves.

“But her eyes - that’s what made me believe her,” John said, “when she told me that she was a queen. They were so blue - not the blue of the shallow water close to the shore, but the blue of the deep, like when we sail into water that goes down farther than we know, and we  see silhouettes under our bow, but never see the creatures that make them when we shine our lights.

“In the moments before she arrived, a great rumble of water reached my ears, and a wave flooded the beach - it came up to my knees, even though I had been standing only at the very edge of the water. It pulled at me as it receded, and queen laughed as I staggered forward. ‘You may approach me,’ she said, ‘but I will warn you against getting too close; I have not eaten yet tonight, and you tempt me. What is your name?”

“Eat you?” Gregson frowned, interrupting again. “The Mer don’ do that - don’ come out and _warn_ you that you could be their supper.”

“That’s what they do, though,” Murray said, tapping his glass on the table for emphasis, “They lure you into th’ water with their songs, then they embrace you and pull you under th’ water where they tear you limb from limb and eat your inside.”

“Yes, well,” John coughed, “as you can see, thankfully, I was wise enough to _not_ go  for a swim that night, and this Mer _did_ warn me that she was dangerous, though I could see that anyway.”

“What happened next?”

“She asked me my name,” John shook his head, “and if there’s nothing else you remember of this story,  remember this - if you meet a Mer, don’t tell her your name.”

“Superstitious are we, Doc?” Murray laughed, “You didn’t believe us, when you came aboard at first, about the stories.”

John smiled, “Yes, well, it seems I learned from the best, and I have you to thank for it. Don’t know where I’d be now if I hadn’t listened. There are superstitions based on truth, after all.”

“Go on, John,” Stamford implored, nudging his shoulder, “Don’t let these rascals stop you from telling your story.”

“Right, thanks. So I didn’t tell her my name, and she told me that she would make me a bargain - I’d seen her but not been enchanted by her song, so I was no good as her meal, but letting me go as a free man would mean she would get nothing in return for sparing my life. So in exchange I had to tell her a story.”

“A story about what?”

“Well,” John rubbed the back of his head, “that’s the tricky part. She wouldn't take just any story; she wanted one that had a piece of my heart in it, something that mattered, something that she could use to weave into her song, when she lured men into the water as her prey. And I didn't want to, I didn't want to give her something she could keep and use as ammunition, as _bait_ , but I didn’t have a choice.

“So I told her the story of the first girl I fell in love with, back home in England, long before I went to war or went to sea - about her golden hair and how it shone in the sun, about the way she laughed and sang when spring came and the flowers opened again. She had me speak an hour, then two, about my first love. When she was finally satisfied, I realized she had taken that piece of my heart, for through my story I had exposed it to her, and she held it between her fingers.”

John put his elbow upon the table, miming holding something small and delicate between his finger and thumb as his friends watched with rapt attention. John twisted his wrist, as if rotating a gem to catch the light, and the sailor’s eyes tracked his hand.

“Then - before my very eyes - she swallowed it.”

“She did not!” Gregson said, aghast.

“She did,” John nodded, “It glowed all the way down, until I could see it underneath the skin of her belly. But she was too quick, and too dangerous, and I was unarmed - there was no way I could get it back from her. So she made me a bargain again.”

John paused, “She said that she liked my story so much that she would let me go, and she would keep the piece of my heart until I found her again, on another beach. Then I could tell her another story, and if she liked that one better than the first, she would give me back the piece she had taken.”

“You’re full of it, John Watson,” Gregson shook his head, shifting his chair back to head to the bar for another mug of beer, “If you’ve got a girl on some island or another that you’re bedding, jus’ tell it like that.”

“But it isn’t like that,” John gave Gregson’s retreating back a small smile, “You’d do the same if someone made off with a piece of your heart, believe me, especially if that someone could eat you.”

“Blimey,” Murray sucked in a breath, though a smile was bright on his flushed face, “I’m going to need another drink.” He slid out of his chair, resting a hand on John’s shoulder when he stood and nodding to him for a story well told.

“Is it true, John?” Stamford asked, his gaze filled with awe and no small portion of doubt.

“Do you want it to be?” John smiled, but it didn’t reach his eyes. Stamford didn’t reply, but his eyes stayed locked on John as the doctor stood and walked around the table to put his hand on the wooden back of Stamford’s chair.

“If you do want it to be true,” he said softly, “It doesn’t really matter, then, does it?”

 

•

 

John had no doubt that his mysterious exit from the tavern had perplexed his crewmates, but a wry smile quirked the corners of his mouth. Whether they believed it or not, his story gave an air of mystery to his absences that they would leave well alone, John hoped. He left the cobbled streets and thatched roofs of the town behind him, heading for the white-silver slip of shoreline he’d seen from the decks of the _Zephyr_ when they’d made berth. The moon was a perfect eggshell half above him, illuminating the curve of the hill as he all but jogged to the beach.

Light reflected off the mica in the sand, white-blue, as John approached the line of the waves. A craggy cliff met the water to his left, rugged outcroppings of rock heavy with moss and lichen, beaten smooth where the waves could reach. The water beneath was darker, mottled with browns and reds and greens; coral, John knew, though the colors looked more vibrant in the light of the sun rather than the moon. The worn, barnacle-encrusted rocks protruding from the water would do well for what he had planned; John shucked his shoes with his toes, and stepped into the warm ocean.

He waded up to his waist, to a rock hidden from the sight of the shoreline, tucked into a collection of taller rocks that had broken off from the cliff and fallen into the sea long before. The barnacles stung his bare hands and pulled at his wet breeches, but John hoisted himself up to sit on the flat, angled surface of the rock without problem. It seemed the water was good for his injured shoulder; he stretched it and rotated his arm, the ritual of loosening the knotted muscle a comfort as he settled down to wait.

It didn’t take long. A shimmering movement underneath the water caught his eye, and not a moment later Sherlock was surging out of the calm surf, arching his back to shake water out of his dark curls and off of his face. The action drew John’s attention to the sharp lines of his collarbone and neck, and he blushed as he remembered pressing kisses there - and dreamed of doing more, in his altogether too warm cabin when they were at sea. Sherlock blinked the salt from his eyes and caught John watching, and smirked as he swam closer with sensual movements that made his muscles ripple beneath the surface of his skin.

The Mer put his hands on either side of John's knees, pulling himself far enough out of the water to place a tentative kiss at the corner of John's mouth. John smiled, one hand coming up to rest on the small of Sherlock's back. His skin there was cool and slick, but warmed quickly from the heat of John's palm.

Sherlock pulled away, eyelashes brushing at John’s cheek. He took in John’s appearance and frowned, sliding further back into the water. “What is it?”

“Nothing,” John said, unsure what the Mer could be referring to, “I’m glad to see you.”

“And I you. But-” Sherlock shook his head and narrowed his eyes, “did you - you met my _mother_?”

“She came to me as I was waiting on a beach for you a few days ago,” John admitted, “but-”

“ _You did not say her name_ ,” Sherlock bit out, crowding closer again in agitation, “Tell me the truth, John. You did _not_ say her name.”

“No, I didn’t!” John held up his hands, appeasing, “I knew not to, you berk. I may not have been born a sailor but I’ve become just as superstitious, and I know the weight of a name.”

Sherlock blew out a gust of air, but the lines of his neck still stood in sharp relief with nervous tension. “Good. That is...good. If you had said her name, you would have been beholden unto her. She still got to you, though. She still found out who you are.”

“Nothing happened,” John said softly, “Really, nothing. We spoke, she made vague threats to my person and implied things I didn’t understand - you lot like to be mysterious, you know - and I’d meant to tell you about it, but-”

“John,” Sherlock sighed, leaning forward to rest his head in John’s lap, “be quiet a moment.”

John blinked down at Sherlock in surprise, careful not to kick the Mer in the ribs with his feet, which were dangling in the water. He rested a tentative hand on Sherlock’s head, carding through the dark, soaked curls that were beginning to dry stiff with salt. Sherlock made a soft murmuring hum deep in his throat, which John could feel where their skin met. In increments, Sherlock began to relax, the agitated movements of his tail beneath the water turning supple and languid, his back rising and falling with the deep breaths he took. He was a warm, pleasant weight, and John found himself enjoying the peaceful, domestic quiet of sifting through Sherlock’s curls and breathing together. John synchronized his inhales and exhales until Sherlock grew restless, shifting in John’s lap and then sniffing and nuzzling in exploration.

“Sherlock,” John warned, anticipating the rush of blood to his groin that his motions would cause. Sherlock looked up at him through his dark fringe, eyes playful and predatory.

“I am curious about you,” Sherlock smirked, “I am curious about you _here_.”

“Believe me, it’s curious about you, too,” John said under his breath, and Sherlock’s head snapped up fully.

“ _It_?”

“Later, Sherlock,” John cupped Sherlock’s face with his hands, brushing away the clinging salt from his eyebrows and the high crest of his cheek, “Shouldn’t we talk about your, erm, mother?”

Sherlock rolled his eyes “If you must bring her up, yes.”

“You could have told me she was the _queen_ ,” John said, “or that you’re her son, that’s really the important bit. Does that make you a prince?”

“Only by your human perspective of familial relations and royalty,” Sherlock replied, frowning, “It is not important. She is my leader, not my mother in the way that humans see family.”

“That’s - what she said, too,” John said slowly, frowning.

Sherlock fixed him with his pale, flinty eyes, his eyebrows pinched in wary curiosity. “What else did she say?”

“Well,” John looked upwards, trying to pull the phrases from his memory, “she called you...singular. She said I was loyal - though that bit sounded more like an accusation. So did when she called you singular, too, actually. And she said you didn’t exactly know what was going on between us.”

“She was not lying,” Sherlock set his chin in his hands with his elbows on John’s rock, in the space between John’s thighs. John willed himself not to get distracted by Sherlock’s proximity, or the tempting wet curve of his lower lip.

“About any of it?”

“All true,” Sherlock nodded, “I am singular among the Mer, even if I wish I were not.”

“Not just in that you are the only male,” John guessed, watching as Sherlock’s eyes flicked up to meet his before casting away again.

“Yes. She told you that much, did she?”

“She rather liked to hear herself talk,” John huffed, “a trait you seem to share.”

“We have similarities because we are kin, and because we are Mer,” Sherlock said, “I get my looks from her, though it is altogether a mystery as to why I am male among my clan when no others are.

“Does it have something to do with the fact that she’s the queen?”

Sherlock shook his head, curls brushing against the bare skin of John’s legs. “No, I do not think so. I asked her about it, when I was much younger, but I have no interest in hearing an answer that involves the details of the sailor she chose to bed on the eve of my conception.”

John shivered, shaking his head, “No, I don’t suppose anyone would.”

“She is wrong only retroactively,” Sherlock continued, “I did not come to you the night that she did because I was finding answers for myself, after you had mentioned that something was amiss with your compass. It was a mystery worth investigating.”

John couldn’t resist. “Did it hurt you, just then? To admit that you didn’t know something?”

“Hush,” Sherlock rolled his eyes, “I trust that you believe enough in the magic of this world to understand what I am telling you, and it will be worth your attention to listen - this concerns you as much as I. Did you bring it with you?”

“Yes,” John pulled the compass from his pocket; it had gotten wet when he had waded out from the shore, and the wood gleamed in the moonlight. Sherlock took it and turned it in his hands, examining each of its sides and peeking in on the face of the compass itself, lips pursed. Sherlock’s eyes flitted away and he scratched nervously at the hair behind one of his glistening ears. John stared, a pit of apprehension forming in his stomach.

“ _There is an older magic at work_ ,” John repeated Aeserena’s words, and Sherlock startled, wide-eyed at the phrase from John’s mouth, “ _older than the Song_.”

Sherlock swallowed. “Yes,” he said, voice deep and soft with unease, “The Song is not just our method of hunting, though  using it as such has been advantageous in recent times. It is the old form of Mer magic, given to the queen - my mother, the mother of all Mer.”

“And - there’s magic that is older than that?” John asked.

“Of course,” Sherlock replied easily, “The Song is our own, but we are bound by the laws of magic, as are all beings. Humans are as well, though you choose to bind yourself in even more laws, and rarely do you come up against the barriers where magic would hinder you.”

“Sherlock,” John said, “Please, just - explain, whatever it is.”

Sherlock’s lips drew into a thin line. “You will not like it,” he warned.

“Let me decide that for myself,” John huffed, “I can promise I won’t run away again.”

“You might wish you could,” Sherlock said quietly, cheeks pinched as he grimaced. He shifted, laying his large hands over the caps of John’s knees in a steadying gesture. John wasn’t sure if it was to reassure him, or if Sherlock was trying to anchor himself before he spoke.

“Names are a tricky thing, and by not giving me your true name when I tried to enchant you with my Song when we first met, I was unable to lure you into the water as I had planned. Then, you did something so wonderfully unexpected -” Sherlock shook his head, smiling ruefully, “- you asked for _my_ true name, and in exchange gave me an item precious to you to keep in my possession.”

John knew what came next. “I returned it, in due time, but something had already begun - something that only grew stronger, when you told me your true name and then sealed it with a kiss.”

The knot of unease in John’s gut gave way to clouded curiosity. “When you put it like that, it sounds rather like -” John’s voice stuttered, “- betrothal.”

“Not... _precisely_ ,” Sherlock said, his fingers flexing on John’s knees, and John tilted his head. _Not precisely_ wasn’t _no_.

“There is not an exact word for it,” the Mer admitted, “Magic older than the Song is not always definable by language. We are bound to each other, now. We wove the bonds as soon as I told you my name, and irreversibly so when you gave me yours; kissing me only bound us closer.”

“Sherlock,” John said softly, “I’m pretty sure we were already bound to each other at that point.”

Sherlock eyed him, adjusting his grip to lean in towards John. “You mean in a different way,” he said slowly.

“We’ve been drawn to each other ever since we met; surely you’re not going to attribute _all_ of that to mag-”

“John,” Sherlock closed his eyes, heaving a deep breath, “this is not something I can have.”

“What do you mean, can’t have?” John frowned.

“I am dangerous.”

John rolled his eyes skyward, shaking his head, “We’ve been over this; I like-”

“I am _dangerous_ , John,” Sherlock snapped, eyes blazing silver in the moonlight. His lips pulled into an angry sneer, revealing neat rows of pearly, sharp teeth, “The Mer do not and never have formed anything like friendships, or - or _more_ , it is not in our nature. We are vicious - we _eat_ your kind to survive, John, and we revel in the cruelty of luring sailors into our arms and sealing their fate in the sea. I cannot have this," he repeated, "and you should not want it."

"It - this, our friendship?" A sick, rolling unease formed in John's chest, "You say ‘ _we’_ but - but you aren't like the rest, Sherlock, you are far more intelligent and curious about humans. No harm has come to me-"

"Yet," Sherlock hissed, " _Yet_. For the entirety of our acquaintance, _yet_ has been hanging over us. Do not forget that, and do not think that because we have kissed that _yet_ will never come to pass."

John leaned back, a warm blush of anger taking the place of his wariness. "That has never stopped us before, Sherlock. The balance of danger is what makes our acquaintance interesting, but I want to believe that if we can trust each other-"

"You cannot trust me!" Sherlock shouted, "I-"

"Stop telling me what I can and can't do!" John shouted back, "I'll do as I like and I’ll be friends with whoever I want to bloody well be friends with, Sherlock!"

Sherlock was quiet, ears flattened against the side of his head, “Relationships exist in two directions,” he said at last, "If I must, I will remove myself from you to ensure your safety.”

John frowned, still not pleased at the way the conversation had turned. “Sherlock-”

“Please, John,” the Mer said, tone soft and deep, a  note of pleading in his voice, “I do not mean to imply that I should control what I think is best for you, to punish you in any way. You still do not know  what I have discovered,” he  admitted, his pale eyes slipping from John’s face to the shore beyond.

“Tell me,” John replied. “You can keep avoid the issue, or you can tell me what it is and we can try to solve it. Or if we can’t, we can find a solution that at least allows us to be friends. Don’t-” he held up a hand when Sherlock opened his mouth, presumably to complain about the fault in John’s plan, “- don’t tell me it’s stupid, or it won’t work, not until we hash this out. If it really is for the best, then we can end it. But don’t rob me of the choice.”

“I cannot promise you anything,” Sherlock sighed, looking as ill at ease as John felt.

“I know,” John said, “and maybe that makes you wise, but I won’t so easily give up something I care about without hearing everything first. So.”

He gestured for Sherlock to speak, but the Mer was staring at him, eyes inscrutable and measuring. It was a look John had often seen on Sherlock’s face, but with the pale light of the moon and the faint patterns of light reflected from the water, Sherlock’s eyes were soft and surprised. John clenched his teeth at the realization that he had readily admitted that he cared about Sherlock. He wouldn’t take it back - it was true - but it made him wonder how little Sherlock had heard those words coming from anyone, if he had _ever_ had them spoken to or about him at all.

“When the Mer take mates,” Sherlock said, haltingly, as if the words pained him, “I imagine it is nothing like human coupling. The Mer enters a frenzy until she find someone suitable, and lures them into the water with her Song, using everything in her power to bring the one she has chosen into the sea.”

A shiver ran down John’s back, his eyes riveted to Sherlock as he spoke. The Mer’s s tail made snakelike whirling patterns in nervousness, all coiled tension and subdued power.

“The Mer brings him to her keep, where in her frenzy she has created a place for them to lay together. She allows him to have his fill of her flesh, and takes his seed into her body; then, she has her fill of his,” Sherlock swallows, the apple of his throat bobbing at the motion, “Do you understand, John?”

“You mean,” John said slowly, “it’s not just when Mer are hungry, when they want to hunt- that _after_ \- the Mer, they- ”

“They eat their mates, yes,” Sherlock smiled humorlessly, “They gorge on their human’s flesh, feeding the child that grows within them on the meat of the parent. It has always been so, it has been woven into the Song we sing to our children since generations far lost to memory.”

John shifted on the rock, suddenly painfully aware of the sharp press of barnacles into the bare skin of his legs, and the hair on his arms rose as another shiver went down his spine.

“You said _she_ ,” John pointed out.

“Yes,” Sherlock nodded, “You would notice that. I have observed it happening to my kin, but the frenzy has never taken hold in me. It is possible that it never will, as I am male and cannot conceive in the way my sisters can.”

“But you’re worried it will,” John scrubbed a hand over his face, trying to rub some of the tension from his eyes. Jesus, Sherlock was worried that he would _eat_ him.

“It is a legitimate concern,” Sherlock rose off his elbows and slid neatly back into the water, watching John warily. “Does it not worry you? Sicken you? That there may be a part of me that wishes to feast on your flesh? That this part of my nature could flare to life the more we are intimate?”

“When you put it like that,” John snorted, pulling his hands away from his eyes to knot them together, wringing them in his lap as he thought. He licked his lips, then stopped partway through the motion as Sherlock’s eyes latched onto the movement of his tongue.  He flushed. “But is there any real danger of that coming to pass? I know I have basically no experience with Mer, but-”

“Is there any _real danger_ that I will _eat you_?” Sherlock snapped, “Is the threat of your death at my hands not dangerous enough, John?”

“That isn’t what I meant,” John said stiffly, a frown creasing his brow.

“I do not know what it is you _did_ mean, then,” Sherlock gripped John’s rock with his fingertips, the skin around his nails turning bone-white as he pressed down harshly, his biceps standing out against his skin in a show of strength and ferocity as the Mer sneered. “You are not _nearly_ as afraid of me as you should be, John Watson.”

John’s heart beat a steady rhythm in his chest, already increased from the fervor of their disagreement, but it surged at the Mer’s words and the sight of him, all corded muscle and dripping water, light bouncing off the silver of his scales and the glint in his eyes that was, John knew, _very_ dangerous.

“I am afraid,” John admitted softly, daring to lean forward into the Mer’s space. Sherlock’s nose twitched, nostrils flaring as John’s warmth moved towards him, his breath ruffling the dark curls that had dried and were now moving, wisp-like, with every breeze. “But of what you have already done, not what you could do.”

“John,” Sherlock’s eyes were deep black, his pupils a pale ring that John barely glimpsed before Sherlock’s mouth was on his, and his eyes shuttered close.

This kiss was all teeth and tongue and heat, no tenderness between them, the heady pulse of adrenaline and lust in their veins. Sherlock bit at John’s lower lip savagely, the sharp points of his teeth grazing the sensitive skin, leaving it prickling with heat and pain-pleasure. He laved over the scrapes with his tongue, smearing the bead of blood he had drawn to the surface. John gasped into Sherlock’s mouth, an invitation Sherlock took with his tongue, swallowing the noise. John could taste himself on the Mer’s tongue, and gave as good has he got - stroking Sherlock’s tongue with his own, pulling his lip between his teeth to bite gently, and sucking until Sherlock moaned, a ragged thing torn from his throat in a desperate, needy cry.  They struggled and surged against each other, until John was finally able to get a hand into Sherlock’s dense curls to pull him away from his mouth. Sherlock’s hands continued to roam over the tense muscles in John’s thighs and grab at his waist, pushing and pulling and tearing, unable to decide what he wanted.

“Sherlock,” John breathed, panting into the small space between them. He clutched at Sherlock, flexing his fingers in the dark, soft curls, and cupping his hand and gently tugging to bring Sherlock’s forehead to his.

“You are afraid,” Sherlock said hoarsely, sounding as wrecked as John felt; the sound of it tore at John’s heart.

“Yes,” John said weakly, pressing forward to slide his nose along Sherlock’s, his flesh cool and damp in the night air.

Sherlock’s cheek was flushed hot against his, though, as he turned  and pressed their faces together. John felt the feather-soft brush of Sherlock’s eyelashes as he blinked, then closed as his eyes.

“As am I,” Sherlock replied softly, exhaling a heavy breath that rattled in his chest. John’s fingers slipped out of his hair as the Mer pulled away, eyes bright as they connected with John’s, and John felt his own breath catch.

“You told a story tonight,” Sherlock said, a  sad smile twisting his lips.

John didn’t bother asking how he knew; it must have been in the details of his person, in the slant of his mouth or the way that he kissed, but the details didn’t matter. It still added up to Sherlock knowing, correctly. “Yes,” he said, blinking calmly at the Mer.

Sherlock tilted his head, “About me or about my mother, I am not sure. But about the Mer, nonetheless.”

“A bit of both,” John nodded, a blush rising to his face at the thought of what exactly he’d spun into his tale. The description of the femininity was all Aeserena - long hair, luscious curves, pearls, sharp smile, and sharper, harsher words. But the rest was all Sherlock, from the deep dark of his curls to the depth of the eyes John had described, the silver hammered-penny scales of his tail, and the story in exchange for the piece of his heart. John swallowed.

“I-” Sherlock looked away, and John watched the water lap at his chest as his tail made languid movements back and forth in the dark, clear water, “I cannot fault you, but part of our agreement was that you would keep us a secret.”

John’s blood ran cold, “You know that I - when I told that story, no one believed me - it was a story for the sake of storytelling, not to try and convince anyone that you are real, or for the purpose of hunting you down-”

John’s voice stuttered and halted in his throat when Sherlock held up a hand to quiet him, his jaw clenching closed as he watched something change in Sherlock’s face. The softness and tender hesitancy sloughed away, leaving in its place the cool, calculating expression Sherlock had worn when they first met.

 “John,” Sherlock said, “By telling your tale, you have infringed upon the terms we set forth at our first meeting.”

John swallowed, his heart lodged in his throat.

“I do not know the impact that will have on the magic binding us,” Sherlock murmured, “if at all. I must admit that at the time we agreed upon those terms, I did not know you as I do now. Perhaps it is time for us to do away with an agreement so formal.” His face blossomed into a small, fond smile, and despite the nervous pounding of his heart, John found himself smiling back.

“So what do we do?”

“There may still be more that I can learn,” Sherlock said, reaching forward to lace their fingers together, Sherlock’s right hand with John’s left, “It would be wise to ensure that no ill has come of the story you have told.”

“I really don’t think anyone believed me,” John sighed, rubbing a hand through his hair, “but I’ll know for sure when we head out to sea, what my mates thought of it. I’ll convince them it was just a tale, if I need to.”

Sherlock nodded, “That will give me time to research and learn what I can of this magic.”

He hesitated, and John gave his hand a squeeze.

“Logically, I know that fear is a rational response to our situation,” Sherlock said, “for both of us. But – I refuse to let it rule my head. I will look into the other matter, as well. It is possible a solution – or at the least, more information - exists.”

“I believe that-”

“Belief has little to do with it, John,” Sherlock shook his head, “I will not be assured that you are safe around me until I have solid proof; twisting facts and assumptions to fit a conclusion rather than gathering evidence first is unwise.”

“I’m sure I’ve proven some of your conclusions wrong, then,” John chuckled, and when Sherlock frowned, he leaned forward to kiss his pout away.

“I will never regret meeting you,” Sherlock said softly, and John grinned, “Proving me wrong as you have has been…illuminating.”

“Yeah,” John said, “It’s been…good.” The word felt thick in his mouth; it was so much more than good. But Sherlock seemed to understand, and he smirked at John, sliding his hand up to cup John’s cheek.

“It will be great, John,” he said, “You’re _mine_ , and will be mine; it may be some time before I return but I will return for you, John.”

The possessive growl in Sherlock’s baritone sparked heat in John’s gut again, and he smiled, face warm, as Sherlock kissed him once more and began to pull away. A wind had kicked up as they spoke, and ruffled Sherlock’s hair as he slipped back into the water

“Another moon, then,” John hummed as the Mer swam further away, out to sea, “I’ll see you in another moon.”

The waves grew around him until they were brushing against John’s knees, surging to life as the wind stirred the surface with surprising, sudden force. John didn’t risk a look at the shore behind him, eyes trained on Sherlock’s form until he was swallowed by the curl of a breaking wave, severing their locked eyes. When the wave passed Sherlock was gone, into the roiling depths of the sea.

John blinked the salty water out of his eyes, a mist now kicked up by the white-capped waves, matting his hair and clinging to his eyelashes in fat, wet droplets. John slid off the rock and into the water to head for the beach, only just visible - clouds had obscured the bright face of the moon. He was quite distracted, John thought, to not have noticed the storm brewing in the sky as he and Sherlock spoke.

The waves battered him, pushing him towards the sandy shallows and soaking him to the bone with each that rolled and ebbed and ploughed against him. The clattering of small stones and shells at the shoreline sounded like bones to John’s ears, like the ocean was a hollow, breathing thing with a sick rattle in its lungs. Sand sucked and grasped at his feet, wet and muddy as he finally emerged from the surf, skin slick and sticky with salt and grime.

Only when the shore was a distant scar between the line of dark trees and the moving water of the surf did John wonder if, perhaps, the storm was tied to him and Sherlock. The thought lingered in his mind as he wound through the trees, as he jogged across the windy deck and into the ship. He curled up on his side in bed, safe in the belly of the _Zephyr_ with the storm howling outside. There was little he could do now but wonder as rain battered at the ship, his mind clutching at Sherlock’s words for comfort.

Beside him, opened on the sheets like a dark shell, the compass held steady. The candlelight flickered on the hammered metal of the arrow, but all night, as John watched, it didn’t move.

  
•

 

John barely slept. After having two weeks of blessedly restful sleep, his body revolted against the clinging wakefulness that came when the sun set and the moon rose. Each night, John tracked the stars as they tilted across the horizon, spinning above him until dawn broke and flooded the sky with grey-pink. His nights were restless and his days lethargic, his eyes haunted by the ghost of a sleep he couldn’t reach, a worry that ached and wouldn’t leave his mind.

The _Zephyr_ continued to sail through bad weather as she traveled south, into the even warmer, shallower havens of the Indies, at the far reaches of their route. The ship was blown further east than Lestrade had anticipated, one night, and they spent the entirety of the next two days tacking against a hard wall of easterly winds in order to regain their course. They were three days off their expected schedule by the time they made berth at their farthest port of call, and still the horizon was dark and grey from morning to night, with only temporary lapses in the otherwise steady rain.

John hadn’t seen the stars in a week by the time they headed north, restocked with food and water and barrels and boxes of cargo that made the _Zephyr_ sit low and heavy in the water. It wasn’t properly storming, but the wind was strong enough to make the pulleys clack as the sails tugged and heaved in their ropes, wave after wave rocking the _Zephyr_ port and starboard like a cork bobbing in the frothing water.

The crew laughed, saying the ship was living up to her name. To John, it was exhausting, all the more so because he barely slept.

When he did dream, he dreamt of Sherlock.

Every splash of ripples on the surface of the sea made his insides jump as if they were on a taut string, eyes drawn to the water like magnets. John kept his own compass on the table at his bedside, staring at its worn designs for hours in dim lamplight as sleep refused to come to him night after night.

The nights they moored in port, John still spent on the beach, though the Mer had yet to appear to him again - neither Sherlock nor his hard-hearted mother, to John’s endless worry. It was entirely possible that the storm had nothing to do with the Mer, with the bond they had wrapped around each other; still, it unsettled him.

John was a practical man. He had once been listless and lifeless and hopeless, wishing that something would happen to give him purpose, with which to move forward. And he had found that, with Sherlock; he no longer looked expectantly towards death as the next point on a map that he was steadily moving towards. He was profoundly grateful; but without Sherlock’s presence to anchor him, his worry was a heavy burden he couldn’t convince himself out of. It was the smart course of action, for Sherlock to find out what he could – better than him flat-out denying that any friendship between them was impossible. John was stubborn; he wouldn’t let Sherlock rob him of that choice. But Sherlock didn’t know, couldn’t deduce what his biology would do; John understood that for Sherlock, _not knowing_ was the biggest fear he could harbor.

More often than not, John returned from the beach with cold settling under his ribs, feet uncomfortably sandy and with salt slinging to his calves. He still felt like he was being watched, but he couldn’t be sure that the sensation wasn’t just wishful thinking.

 

•

 

A full moon came and went, and the _Zephyr_ made another full circuit of the Caribbean.

Sherlock didn’t appear.

•

 

If John’s companions noticed his returned stiffness, or the disinterested regard he took in the travels of the _Zephyr_ , they didn’t comment on it. They still invited him to the pubs when they went ashore; he still joined them, if much quieter. The worrying and over-thinking was fraying his nerves, and John knew it. He was careful about walking, sure to stretch his knee and thigh, bending and flexing it in the evenings - but it twinged and knotted in the tell-tale sensation that John’s gut told him was the limp, bound to return.

So when they made berth on the island where he’d first met Sherlock on the beach - and kissed him, sealing and binding them together in a way he still didn’t quite understand - he descended from the _Zephyr_ with a weight in his heart, determined that this would be the last night, for a little while at least, that he held vigil for Sherlock.

His feet knew the way to the shore from the cheerfully lit village, away from where the cobbles turned to dirt underfoot and then gave way to coarse sand, until the powdery white turned fine, and coated the soles of his shoes. He removed them at the pier, taking care to step around barnacles and slick, green patches that had grown on the surface of the old, knotted planks. The tide was high, so when John settled himself on the barnacle-ridged edge of the pier, the warm water swept past his ankles and pulled at his toes as the waves ebbed and flowed.

John watched them, for a moment, the way that his tanned skin looked so pale and translucent with his feet under the water, magnified and tinged blue. The sea was unnaturally clear, where it met the land here; he could see down to where the piles were driven into the sand-mud-clay bottom, patterns and clusters of barnacles and mussels fused to the wood almost flower-like in their blooming arrangements.

What it would be, John thought, to be so steadfast in the face of so much rushing water, amidst so much daily change with the sweep of the tides in and out. Even in the small sphere of his own life, John felt mightily adrift.

John looked up to find Sherlock in the water in front of him.

“Jesus,” John scrambled backwards, pulling his feet out of the water and clenching a hand over his heart in surprise, “Christ. Could you make some noise when you do that?”

Sherlock’s face was half-submerged in the water, almost up to his nose, and his gills fanned out at his neck in delicate trembles. He rose out of the waves to swim closer, tail beating rhythmically in the water. “John,” he said.

“Don’t ‘John’ me,” John frowned, fisting his hands against the now-damp wood in front of him, “Where have you been?”

Sherlock flinched at John’s sharp, demanding tone, eyes wary but measuring and so, so beautiful in the faint light, water coursing down him in thick drops as John took stock of him. John wasn’t like Sherlock; he couldn’t tell what the Mer had last eaten or where he had been from his form, but he could tell that some change had come over him since they had last spoken. Sherlock had lost some of the dense, lean muscle on the line of his shoulders, and his ribs seemed more pronounced. John could see the sharp arches of his cheekbones in higher contrast on his too-pale skin and a hunger in his eyes that lingered, unhidden and unchecked, as John observed him.

John hardened his gaze, attempting to ignore the bloom of heat in his chest that had come with Sherlock’s reappearance, and the reassurance that for the most part he was hale and whole . “Well?”

Sherlock continued to stare at him, blinking quickly before settling his gaze on John’s face, his blue eyes piercing in the low light, “John, I-” he paused, lips pursing as he searched for the right word, “I missed you.”

The pulse in John’s throat jumped at the admission, but he pursed his lips, reminding himself of the weeks he’d spent in worry, with no sight or sign from the Mer.

Sherlock swallowed when John didn’t respond right away, his throat bobbing and his full lips pressing into a thin, white line. “I know I do not have any cause for saying so-”

“You don’t,” John snorted, surprised at the force of his own words, “when you were the one to go off looking for more, to find out more, and then were too busy to return so I would at least know you were alive – and you have the _nerve_ to say that you _missed me_ -”

“It had to be done; I-”

“You what? Are _afraid_?” John knew he was jabbing at bruises, but the words fell off his tongue without heed, “Everyone in a relationship is afraid, Sherlock. That doesn’t make you different from anyone else. It doesn’t excuse you from thoughtlessly leaving me behind.”

“I did not expect to be so long,” Sherlock finally snapped back, eyes stormy and mouth twitching into a sneer, “and you say _everyone_ ; you mean everyone _human_. I am not, and you cannot expect me to act like one.”

“You’re more human than I think you even realize,” John said, “People run when they are afraid, and that is exactly what you did. You left under the pretense of getting more information, of finding out more for us but you – the compass stopped working, I had no idea after that if you-”

“I did not- I did not think it would affect you so,” Sherlock admitted and shook his head, swimming closer, “For that, I apologize. I have long thought on the matter between us and-”

John snorted, “Apologize, Sherlock? I’m not sure you even know what to apologize for.”

“Seeing you now, I do regret that my actions were necessary,” Sherlock huffed, no trace of empathy in his words, “and-”

“And what, Sherlock?” John pressed, the spark of anger hot in his gut now that he had an outlet for what he had fruitlessly buried for weeks, “And what? Would you have done anything different? Could you have, when you’re so used to investigating as you always have: alone?”

The silence that fell was heavy and pregnant, Sherlock’s eyes brimming with something undefined as he stared at John in a way that made the doctor’s breath catch in his throat.

“Why did you come back, Sherlock?” John asked, tiredly. The ache in his bones was more pronounced now that they had stirred the air between them with hard, sharp words. Sherlock teetered, indecisive for the first time; he canted his head to the side, his confidence visibly deflating as he considered what to say. John didn’t know if Sherlock’s care in choosing his words was comforting or unnerving. “I…I did miss you too, you arse.”

“I have…found out more, found something that could be of worth to us, or at least valuable to know,” Sherlock admitted, breaking eye contact. John sighed, and the Mer continued, “and you do not appear...well.”

“Bit not good, Sherlock,” John said, scrubbing a hand over his face. “Without you, my – my limp has returned.”

“A mental affliction, a small matter of-”

“It’s really not, Sherlock.”

Sherlock’s eyes pinched in what John barely identified as meekness, it was so unfamiliar on Sherlock’s face.

“I am not accustomed to this,” Sherlock said, “Caring about the well-being of another, as much if not more than myself - I cannot imagine how you humans do it.”

“Emotion isn’t a choice,” John said mildly, observing Sherlock with keen interest. “I thought you had started to see that.”

“I…yes,” the Mer agreed quietly, “I suppose I am learning that it is not a choice, indeed. I will not make excuses for myself but I can try to explain my actions, and perhaps that will clarify why I have returned to you, and why I was away for so long.”

John considered Sherlock’s words, and he finally waved for him to continue. “Go on, then.” He clung to the bitter tang in his mouth from Sherlock’s weeks of abandonment, the unease in his gut; but John couldn’t help but thrill, at least a little, at finally getting to see the Mer again.

“You told me that you were afraid,” Sherlock said, bright eyes locked on John and his voice unsteady with quiet honesty, “and that was wise, I thought, that you were afraid of me. I told you so when we last met. _I_ am afraid of myself - what I could do to you, intentionally or not. I thought there must be something that could be done, with the Song and the most ancient of magics binding us. I threw myself head-first into searching for something, anything that could benefit us, rather than acknowledge that perhaps there was nothing to find.”

John pursed his lips but didn’t respond; yes, that had been the bulk of his fears that night so long ago.

Sherlock’s tail fluttered nervously in the water, betraying his discomfort at confessing his thoughts to John, not knowing how they would be received. “But it caused you pain, for the time that we were apart - I see that now,” Sherlock said softly, “I cannot deny it - even among all the myriad factors of your life aboard that ship, the only thing that changed with much significance was my presence and lack of it over the course of the past sixteen days - so I was causing you pain, unknowingly, selfishly as I looked for answers. For that, I do apologize. That was never my intention.”

“So it’s pity, then?” John asked, eyes narrowed in a quiet calm of repressed frustration, “Why you’re here?”

“Hardly,” Sherlock rolled his eyes, and then wilted, looking uncertainly up into John’s face, “Is it pity to feel another’s pain as if it is your own? To feel a physical hurt as a result of emotion? I missed you even as I searched, hoped for something to reveal itself to me; for days I wished I could crack open my own ribs, pull them apart to tear at the ache inside of me -”

The Mer lashed in the water, lean arms encircling himself and clutching at his ribs, fingernails dragging at the bone underneath the thin layer of too-pale skin, and John had reached a hand out to Sherlock before he even realized he was doing so. The air in John’s chest seemed to suffocate him, constricting his heart at the thought that Sherlock ached for him, had started to wear away his body as loneliness chafed his mind.

“That - isn’t pity,” John said softly, unable to name the emotion, but from the fragile vulnerability in Sherlock’s eyes John knew that he was thinking the same thing.

“I wonder what you have done to me,” Sherlock mused, slowly unfurling himself from the knot of his own arms, “that I should feel this way. Then, I could not help but wonder: is this what it is like to be under the snare of the Song? Had I deliberately woven myself into a false belief - or worse,” he swallowed thickly, “could it be that what you feel for me is only a product of the Song?”

John blanched, his ears ringing with Sherlock’s words. His mind didn’t work as swiftly as Sherlock’s but he could piece together what he was being told, and the thought made him drop his head into his palms, resting his elbows on his knees as he cradled his suddenly hot face in his shaking hands.

What were they doing?

“Sherlock,” he said thickly, blinking rapidly to cool the sting in his eyes, but then found that he couldn’t continue. He focused on the heat radiating off his skin against the cool of the night, running his fingers through his hair.

“The bonding - thing that we accidentally did,” John finally said, voice muffled and thick from underneath his hands, “Could it actually do that? Manipulate how we feel about one another?”

Sherlock shook his head, "I do not know, but I cannot discount it as a possibility until I am certain. In my research I learned much about traditional Mer bonding, and how it works; we inadvertently followed the steps to a Song ceremony, and while I did not sing to you-"

"Yes, right," John lifted his head, dropping his hands away from his face and into his lap. He licked his lips, meeting Sherlock's cautious gaze.

"Bollocks to what is safe, Sherlock," he whispered, "What do you want from me?"

“John,” Sherlock breathed.

“Really,”  John said, “I have been without you long enough that – well, I respect that you looked for answers, and maybe you’ve found out enough, maybe there is more to know- but I don’t want to be apart from you again. What do you want?”

Sherlock's eyes darkened, clouding with the unnamed tension that coiled between them. He swam closer, still cautious and uncertain of how John would react . His fingers curled over the edge of the pier, pale and almost ghostly in the quiet of the shore.

“I want you,” Sherlock murmured, eyes pearlescent and flashing, “I want to see you and speak to you any and every night, not just at certain phases of the moon. I would have you in the water with me. I want to learn you, learn the language of your body and all of its secret places.”

John swallowed, heat pooling in his gut at being the center of Sherlock’s intense focus and the focal point of his words. The tension between them sparked, their eyes locking and unwavering.

“I want you to teach me about humans,” Sherlock continued, “but especially about yourself. I want you to give me that, of your own volition, not because I have figured out the details through my observation, or because we agreed upon it. I want you to give that to me, to want to give that to me.”

“Sherlock,” John gasped, breath caught in his throat as a feverish blush broke out high on his cheeks.

“I would hold you and have you,” Sherlock’s voice deepened, hushing to a whisper, “I would be your nightly companion, the sharer of your secrets. I would take you for my mate - if I could guarantee you would be safe.”

John opened his mouth to reply but Sherlock shook his head, curls bouncing and shining black in the moonlight, “No, John. It is something I - we - cannot have.” He pressed his full lips together, eyes turning even darker and heavier with longing as he pinned John with his gaze. “I would _consume_ you,” he whispered, teeth gleaming as he gritted them in frustration, “I would consume you completely, and there would be nothing left.”

“I would let you,” John whispered back, wetting his lips before he continued to speak, “God, I would, _Sherlock_.”

At the sound of his name Sherlock’s fingers clenched in the sea-softened wood, leaving sharp impressions as he gripped the dock with fierce strength. For a flash John saw the sharp lines of muscle and tendon outlined against Sherlock’s skin before Sherlock was surging out of the water, landing hard on his elbows on the dock. John’s hands reached out and grasped him about the waist, anchoring him before he could slide back into the sea, his fingers digging into the bony angles of Sherlock’s narrow waist.

“John,” Sherlock gasped, and their lips met in a bruising kiss. John’s tongue was sloppy against Sherlock’s, moving with enthusiasm and long pent-in lust. Sherlock moaned low, the sound reverberating deep in his chest that John could feel, and the Mer whined when John pulled his lips away to rest their foreheads together.

“Sherlock, I-” John shook his head, squeezing his eyes shut; “I can’t, not tonight. But I want to give all of that to you. I want to give that, I want to have that. With you.”

Sherlock tipped forward to balance in the cradle of John’s arms, one hand leaving its death-grip on the pier to card through the short hairs at the nape of John’s neck, and he breathed a deep, shuddering breath. “John.”

“I promise,” John whispered against his cheek, watching Sherlock’s eyelashes flutter, “We’ll think of something, we’ll find something.”

Sherlock pulled away slowly, gaze darting between John’s eyes. “You mean this.”

“I said I promise,” John touched a thumb to Sherlock’s chin, tilting his head to the side to press a kiss to the Mer’s lips, more tender and less frantic now. “If we really mean to try – not to be morbid, but in the worst case – I still want to try, but there are a few things I should settle first.”

A shadow passed behind Sherlock’s eyes and John knew he understood; things to settle, in case of the worst. “Your sister,” Sherlock guessed, and John nodded.

“There is that,” John said, “and - well, as I said, if we are serious about making this work then I’m going to want to spend some time thinking about it. The how,” he added, “not whether I want to. Because I do - want to.”

A small, shy smile crept onto Sherlock’s face, “I know, John,” he said quietly, and bent his head to graze his lips across John’s cheek and then down, to suck at the pulse point nestled where his jaw and throat met, under the sensitive lobe of his ear. John sucked in a breath, fingers flexing on Sherlock’s hips, and the Mer hummed.

“Where will I find you?” Sherlock asked, whispering the words into John’s skin. He pursed his lips; he hadn’t thought that far ahead, but Sherlock was already steps ahead of him. It was a comfort, though, knowing the Mer planned to find him again.

“You’ll have to come to me wherever I end up,” John replied, stroking a hand up and down the damp planes of Sherlock’s back, “I’m not sure where that will be, yet. But won’t you-”

Sherlock raised an eyebrow when John cut himself off, looking abashed even as he bit his lip and considered what Sherlock had told him - what he’d spent many hours thinking of, in the weeks of solitude that he had endured. The Mer’s eyes dilated as they flicked to John’s lips and then up again to meet his gaze. He nodded for John to continue.

“Won’t you do that - um. Nest thing?” John mumbled, unsure of how Sherlock would react. To his surprise a faint blush swept across Sherlock’s cheek, and he ducked his head to nuzzle into John’s neck, dropping gentle kisses onto his skin. “Sherlock?”

“I have never experienced a mating before, John, and as you mentioned - it may never come to a point where I am in frenzy. I have learned much in my time away. I would have you, anywhere you would let me.”

John flushed, and the boards beneath them creaked as Sherlock leaned in and their weight shifted. He was being an awful distraction for the thoughts John was trying to follow, his heart filling with tentative hope and his mind blooming with half-formed plans now that they were once again in each other’s arms.

Sherlock squirmed pleasantly against him when John traced the faint lines of the gills on his ribcage, and John chuckled, warmth filling the space in his  chest.

“And what do you want, John?” Sherlock said, pulling away so that John’s hands slid to rest on his shoulders, “I did not ask, before.”

John looked up at the stars, licking his lips and considering. It was a question he’d asked himself already, that his brain churned over again and again on the sleepless nights, tossed about by the storm when rest evaded him. It wasn’t something he let himself imagine fully.

“I want what you said, too,” he replied, dragging his fingers up into Sherlock’s curls, continuing the soft, eager touches, “I want to see you whenever I can, kiss you whenever I like.”

“And?” Sherlock pressed, because of course there was an _and_.

“And…” John smiled slowly, “I want anything you’ll give me - I want your secrets, I want your dark places and your fear. I want to _not_ worry about what’s between us - I can deal with the danger, if I can feel safe in knowing that you’ll always wait for me and find me.”

“I will,” Sherlock said, “but you must know, John - the Mer are,” he paused, pinning John with his eyes as he spoke, “- _possessive_ , and I am not immune to that part of our nature.”

“Possessive?” John lifted a brow, trying to lighten the mood, but Sherlock’s expression didn’t change from the focus and eager, predatory intensity that sent shivers up his spine.

“Yes, you will be mine,” Sherlock murmured, “but all that I take of you I will give of myself. I will be yours in return.”

John smiled, “That’s all I ask,” he said, pressing a kiss to Sherlock’s temple, then his cheek, and down to the plush fullness of his mouth. Sherlock let him explore, tongue wrapping around and tangling with John's, and they broke apart with a wet smack that set John's blood racing. It felt fast and hot in his veins, rising to the surface of his skin in a blush he was sure spread from his ears down his neck.

"I am sliding," Sherlock admitted, forming the syllables with his lips still grazing against John's own. John released him reluctantly and the Mer returned to the water, trapping one of John's wrists as he wriggled out of his grip and tugging him along.

"I'll get soaked if I come in with you," John admonished, grimacing at the prospect but wishing he could join Sherlock, feel the slick glide of skin-on-skin.

Sherlock grinned, cat-like, "If you are that concerned about your clothing, you may take it off."

John found himself grinning in return, fisting his hands in the hem of his shirt. Sherlock suddenly shot forwards, gripping the wood and perching his chin there, eyes keen.

"John," he said, a mischievous smirk playing at the corners of his mouth, "would you let me explore you?"

"You mean, now?" John swallowed, heat stirring and pooling in his gut, "But-"

"I know I am not gripped by bloodlust or the frenzy now," Sherlock reasoned, "and I desire you greatly."

John didn't reply, watching Sherlock with eager but wary anticipation. Sherlock waited until he saw John's nod before placing one of his hands on John's outstretched foot.

The contact wasn't a surprise, and neither was it particularly pleasant or unpleasant; Sherlock's fingertips traced a cool path along the top of his foot, then swept underneath to press at the arch, and then the thick pad of his heel on the sole of his foot. His skin there had long ago turned to callus, and Sherlock traced it with unguarded fascination; John watched Sherlock's face, rapt as it was on John's own form.

"Do you really find it so fascinating?" John asked, voice warm with fondness. Sherlock looked up from his examination of John's toes, gently flexing John’s foot upwards to plant a kiss on the ball of his foot.

"Yes," he said, running his nose along the inside of John's foot, and John shivered at the sensation, "I imagine because I do not have them myself, and because it is you."

“Well, explore as you like,” John said, giving him a smile that tightened when Sherlock’s gaze grew hot and leering, running his eyes up and down John’s body and not bothering to disguise his attraction.

“I intend to.”

Sherlock made good on his word; he ran his mouth along John’s foot where his fingers had smoothed over the wood-roughened skin, lapping at his toes and making John giggle before drawing out a surprised grunt of pleasure when he slipped one of them into his mouth. He was thorough, and John felt his pulse increasing its tempo as Sherlock flicked his tongue between his toes, swirling around the largest one in broad, lascivious strokes. When John bit his tongue to mute his strangled groans and sighs, Sherlock grinned up at him and slid his fingers up John’s calves, caressing the underside of a knee or the broad plane of his tanned skin, lightly dusted with blonde hair.

John’s wet toes quickly cooled in the night air, but he was thoroughly distracted by the Mer moving inwards, towards the crease where his thighs met, where his blood was steadily rushing and gathering heat in his veins. Sherlock’s hands traced leisurely paths up his thighs, massaging the dense muscle formed from years the physical demands of a soldier, and now a sailor. When Sherlock’s long fingers dug underneath to cup the lush curve of his arse John groaned, doubly so when Sherlock began to knead the muscle with his large hands. He tugged, dragging John closer to the edge of the pier until Sherlock could lean in and breathe in the smell of him, brushing his nose feather-light along the hardening ridge of John’s cock through his thin breeches.

John moaned aloud, hips flexing as he unconsciously rocked forward, towards the heat of Sherlock’s breath, and the Mer grinned at him wickedly from underneath his fringe of curls. John watched, breath coming quickly now, as Sherlock licked his lips and then stuck out his pink-red tongue to lap at the head of his cock through the tight fabric. Sherlock’s fingers flexed and dug into his arse as he nuzzled and sniffed and licked, exploring John’s length and thoroughly soaking his breeches, grinning whenever he noticed a particularly intense quiver in the taut muscles of John’s abdomen. By the time Sherlock reached for the waist of his breeches, John couldn’t remember ever being as hard, and the pink, leaking head of his cock was peeking out of the hem obscenely.

John leaned backwards, supported by his straining hands, as Sherlock peeled the garment down, his eyes riveted to John’s revealed skin like it was the most precious and secret of treasures. John’s cock bobbed freely towards his stomach, flushed red and welling precum at the exposed tip. Sherlock looked on, fascinated, and John’s cock twitched of its own accord, causing him to groan and for Sherlock to glance up to his face in surprise.

“This is _it_ ,” Sherlock said, mouth pursing as he looked down again, but then he smirked, “Does it truly have a mind of its own?”

“It often feels that way,” John replied wryly, gasping when Sherlock inched forward and his warm breath fanned over John’s exposed cock.

As before, Sherlock first investigated with his fingers, smoothing over the crease where John’s thighs met his body and the strong arch of his hipbones, through the trail of hair that led from his navel down to his groin. He seemed particularly enamored with it - because he had none of his own, John assumed - and Sherlock’s nostrils flared as he scented there. The underside of his chin brushed against the head of John’s cock with his every movement. He moved with deliberate patience, mapping John’s tanned flesh and pale alike, his attention drifting steadily inwards as he explored with every sense. Sherlock’s dark curls brushed against John’s stomach as he finally bent his head to lap at the head, and John screwed his eyes shut with a keening moan.

When he managed to wrench his eyes open again, Sherlock was staring, amused and smug at the reaction he had produced. “Sensitive,” the Mer said, and kept his eyes locked on John’s as he dipped down and licked at the drop of clear fluid seeping from his slit, making broad, gentle strokes with his tongue until the head was glossy and shiny and John’s thighs had started to quiver. “And exquisite.”

“Sherlock,” John murmured, voice thick with lust, not quite sure what he was asking for, but the Mer chuckled deeply. His cock twitched again when Sherlock’s long fingers encircled the base, delicately tracing the veined underside and pulling it away from his body so that Sherlock could fully envelop the head in the slick warmth of his mouth.

John gave a muffled shout that rang out in the quiet solemnity of the beach. His elbows buckled, and unable to support himself he slumped flat on his back, clenching his hands in the fabric of his breeches and trying desperately not to thrust into the velvety wetness wrapped around his cock. _God_ , Sherlock’s _mouth_.

Sherlock pulled off with a wet pop and John could feel his smile as Sherlock rested the blunt head against his lips teasingly. “You want to watch, do you not?” he asked, “I have noticed you watching my lips. Is this what you imagined?”

“ _Fuck_ , Sherlock,” John gasped in reply; Sherlock’s words caused his lips to rub tantalizingly at the underside of the glans, and he lapped at the taut line of tissue. Yes, this is one of the things he had imagined; Sherlock’s lips silky and wet on the hard flesh of his shaft, wrapped around him in a perfect ‘o’ as he swallowed him down. He’d pictured Sherlock like this, eyes bright with lust and self-satisfied with the knowledge that he was bringing John to pieces. But now, as much as he wished he could have, he could not summon the strength to watch; he feared that if he did it would be over too soon, and John wished he could draw out this moment forever.

Sherlock seemed to understand this, read it in the lines of John’s body, and he chuckled again. After a long beat Sherlock hummed, beginning a stroking movement up and down his cock with the ring of his forefinger and thumb, drawing his mouth over the crown of John’s cock again and swirling his tongue around it. John’s back arched, and he planted a foot on the pier next to Sherlock’s shoulder, wriggling under Sherlock’s ministrations.

It wasn’t long before Sherlock’s attention shifted again; he continued the luxurious, slow but steady pace of his hand and kissed down to John’s sac, his other hand moving up to fond and roll his bollocks. His tongue was soft and hot against John’s over-sensitized skin, and John whined, blushing a ruddy pink down to his chest. The dizzyingly pleasurable sensations and the knowledge that they were so exposed, out in the open of the starlit beach, made him flush even hotter. He was laid bare, uncovered and harder than he’d ever been, with his thighs bracketing another man between his legs - who, John realized with a flutter in his stomach, had all but stripped him already, and now John was incredibly naked under Sherlock’s scrutinizing, ever-observant gaze. It made him writhe, dirty and wanton and eager under Sherlock’s hands and mouth.

Sherlock sucked, slipping one of John’s balls into his mouth and laving it with long strokes of his talented tongue, humming so that the deep vibrations sang along John’s skin. It elicited a gasp, and he gave its twin a similar treatment, cradling and squeezing them both in one broad hand as they drew closer to John’s body. Sherlock’s smirk was a line of hot heat on the inside of John’s thigh before he bit, gently, and John swore a litany of blasphemes at the dark sky above. The sting faded and adrenaline and lust pounded heady in John’s blood as Sherlock kissed at the mark he’d left with satisfaction.

John shakily levered himself up onto his elbows, the muscles in his shoulders pulling tight and taut with the effort, and he groaned at seeing Sherlock’s dark head between his thighs. He shivered, caught between feeling overheated and sensitive and cool as sweat formed a sheen on his skin. Sherlock’s every touch was electric, and meeting his eyes only compounded the deliciously trapped feeling in the pit of John’s stomach that sent his cock bobbing and leaking again.

“You trust me,” Sherlock said; it wasn’t quite a question, but John nodded anyways. Wherever Sherlock led he would follow, and he surrendered his body freely for Sherlock to touch and explore. He hadn’t been disappointed so far; indeed, he was teetering towards the precipice of pleasure as Sherlock drew sensations out of his skin as he had never experienced before.

“Yes.”

The fingers on his sac left for the sanctuary of Sherlock’s mouth, and John watched, entranced, as the Mer pushed them between his lips and coated them thoroughly. They were glistening wet when Sherlock removed them, and John flexed his fingers unconsciously as they disappeared from his sight, down to the sensitive skin behind his balls.

John tried to keep himself from tensing but the touch was foreign; he had barely ever explored himself here, though he was determined to prove his trust to Sherlock and let the Mer bring him pleasure. A frown of concentration creased his brow, though he couldn’t prevent himself from flinching when the cool, slick pads of Sherlock’s fingers made contact.

Sherlock blinked up at him, confident and calm despite the wide-blown darkness of his pupils, betraying the effect John was having on him. The air of playful exploration had left him, his breath coming rapidly against John’s knee as he stroked little circles into this secret place of John’s skin, waiting for the tension to melt out of John’s body to be replaced with soft-limbed pleasure.

“Lie back,” Sherlock instructed, tipping John’s upright knee to the side with a nudge of his head. John stared a moment longer, until Sherlock met his eyes with a broad smirk and motioned again for him to recline. As he did so, Sherlock plucked one of his hands off of the damp wood and placed it in his thick curls, which John sank his fingers into with a hum.

The first whisper-light brush of Sherlock’s fingers made him gasp and arch his back, caught between wanting to draw away from the contact and push into Sherlock’s warmth. He was nipped lightly in response, Sherlock’s rumbling baritone sending shivers over John’s skin as the Mer chuckled, stroking across his hole again with gentle surety. The dark heat curling in John’s stomach ratcheted up a notch; he had never been touched here, and Sherlock was enraptured with his anatomy - especially where he split into two where Sherlock was one.

Sherlock’s fingers fanned out to spread across the expanse of his arse; he cupped it with both hands, tilting John’s pelvis upwards as if inspecting him, bare, in the pale moonlight. The air left John’s lungs at the thought, what Sherlock must have seen - John stretched out, naked for Sherlock’s enjoyment, bare in the most intimate of ways. John’s stomach clenched in anticipation.

The touch of something hot and wet and against his hole made John shout, followed quickly by a drawn-out moan - _fuck_ , that was Sherlock’s _tongue_. He licked broad stripes with the flat of his tongue, down the sensitive skin of John’s perineum to the furled hole that twitched and clenched at the sensation. John’s muscles tightened and relaxed in turn; he wasn’t sure if he wanted to pull away from the strange touch or rock into it, and his body was left in limbo between shame and overwhelming pleasure.

John tossed his head side to side, face drawn into a grimace of pleasure even as he flushed deeply in embarrassment. “Sherlock,” he whined, chest heaving as his breath now came in steady pants and heady gasps, “Sherlock, what are y- _nngh_.”

His voice stuttered and died in his throat as Sherlock’s tongue began drawing wet concentric circles around his hole, pushing closer each time until he was brushing the pink, puckered muscle with each pass. John was only barely aware of the low-level whine that he was making, unable to stop the sounds from clawing their way out of his throat. His groans increased in pitch as Sherlock finally rested his tongue against his hole, wriggling and curling it as the muscle fluttered and clenched. The Mer stiffened and pointed his tongue to press inwards, nose grazing the slick cleft of John’s arse as his tongue loosened the ring of muscle in hot, probing thrusts.

Beads of saliva were beginning to run down John’s arse from Sherlock’s fervid attention, and John shivered at the sensation; the wetness cooled as it moved away from the heat of Sherlock’s mouth and the burning pucker of his hole, pooling where his thigh met the wood of the pier in an obscene puddle. John moaned.

Sherlock hummed against him, slippery sounds continuing to reach John’s ears as he was thoroughly eaten out, the tension in his gut building in an enduring crescendo of tight-coiling pleasure. Pre-cum was thoroughly smeared on his belly and continued to ooze from the head of his cock, a clear, viscous strand connecting the swollen crown to the sticky puddle just below his navel. With a sharp inhale at another thrust from Sherlock’s tongue, grazing just inside the sensitive rim of his anus, John pushed back against Sherlock, arse flexing, seeking more friction to chase the slowly gathering orgasm deep in his balls. He could feel it, like a tide rushing up towards the surface in his veins, pulling him along in shuddering waves of pleasure. His blood thundered in his ears, a roar that made him forget the beach, the sea, the stars above, and narrowed his world to Sherlock’s mouth against his skin, hot wet heat in that sensitive place that had never been touched.

John was dizzy and writhing by the time Sherlock pulled away to nuzzle his thigh, replacing his tongue with the blunt pressure of his thumb for John’s hole to clench around as he feathered kisses and nibbled at the dip in his flesh where arse met thigh. Somehow Sherlock knew exactly what he needed; John sighed at the new, bigger intrusion stretching him, the muscle burning in a way that was pain-bright but heavy with heat and the thrill of anticipation. He couldn’t be bothered to try to muffle his cries of pleasure and frustration, now, so lost in the responses of his body to each and every one of Sherlock’s attentions.

“John,” Sherlock growled, voice thick with lust,  dipping forward again and licking at the twitching rim of John’s stretched hole around his thumb, “I want to see you find your pleasure, _John_.”

John groaned a wordless vowel, hips rocking in a search of release, for friction, but the Mer had pulled away while waiting for John to answer. He could barely remember how to form words, let alone find which ones to use.

John swallowed, fingertips roaming over his own chest and belly and thighs, finally opening his eyes to glance down the length of his own body to meet Sherlock’s gaze. His eyes were wide-blown, nearly black with lust; his lips and chin were shiny with spit, his curls disheveled and mussed from all of the tugging and threading through it John had done with his fingers. But for as wrecked as he appeared, debauched with kiss-swollen lips and high points of pink on his cheeks, Sherlock’s eyes held the steadfast determination that meant, John knew,  that the Mer had what he wanted, and was single-minded in bringing John to the best orgasm he’d ever had.

“Not sure I can, like this,” John finally admitted unsteadily, as Sherlock began to press his thumb further into John’s entrance with rocking, sliding thrusts that dragged John’s mind past coherency within moments. Sherlock grinned, smug, and John fought through the distracting pleasure of Sherlock’s fingers long enough to speak again.

“If you - _touch me_ ,” he exhaled, eyelids fluttering and face heating impossibly more at the admission, and Sherlock’s finger stilled its movements, “And- and your tongue-”

John ground to a halt, unable to give voice to his primal desires, bared and spread as he was already in a hazy lust he’d never before experienced. Sherlock kissed him for the effort, though, high on his thigh and then again on the tip of his cock before he settled further between John’s legs once more.

“As you wish,” he whispered, and removed his hand from John’s arse to take his cock in a solid, warm grip, beginning a moderate tempo with a light touch as he returned his mouth to John’s entrance.

The effect was instant and electric, like lightning running hot between those two points on John’s body under Sherlock’s mouth and hands. The Mer’s lips kissed and sucked at John’s slick, oversensitive skin before his tongue returned. He had apparently catalogued every lick and stroke that brought John the most pleasure, John thought with the giddy, dizzy feeling of sensory high.  Every movement Sherlock made lit pleasure in John’s veins and nerves, flaring hot at the base of his spine in near-unbearable arousal. Tremors wracked his skin, muscles shuddering and twitching as Sherlock worked his cock in squeezing, steady strokes, tongue flicking at his hole in time with the hand on John’s cock.

At some unknown signal Sherlock’s rhythm increased, his mouth a hot brand on John’s hole and his hand tugging surely at John’s cock. He ran his thumb across the sticky-slick crown and slit to draw a ragged moan from John’s abused throat. A shiver ran from John’s nape down his spine and then he groaned, skin burning white-hot and the muscles in his groin and thighs jumping.

His orgasm was blinding in its intensity; John arched his back, tight as a bowstring, and he keened a long, high moan as come pulsed from the tip of his cock in thick streams, striping his skin as high as his chest. His toes curled against the wood, every muscle in his body taut as he was wracked with bone-deep tremors. Sherlock didn’t let up, thrusting his tongue into John’s hole even as it twitched and clamped, swollen and dripping, through the waves of his orgasm. John’s brain was wiped of all thought besides visceral sensation, his moan cutting off to a whine as Sherlock licked softly and played with the loosened rim of his entrance. He gulped for air, slowly coming back to his own body as feeling began to return to his fingers and toes, a satiated lethargy spreading rapidly through his limbs.

John didn’t try to sit up; he flexed his fingers to make sure they were in working order and then scrubbed his hands over his face and through his hair, hardly believing that he was still in one piece after such a shattering experience. He felt broken apart and forged anew, almost boneless and unwilling to move for anything but necessity.

Sherlock had finally stopped giving little kitten-licks to John’s entrance and had set his chin on John’s sweat-slick thigh. John levered himself to sitting with care, aware of the fluid drying on his stomach and arse, and wrinkling his nose when his semen dripped down his side.

Sherlock chuckled, eyes bright and pleased, meeting his gaze with a tender fondness that made John’s stomach flip for reasons completely apart from what they had just done. He leaned forward, ignoring the mess to cup Sherlock’s cheek and kiss him, thoroughly and gently.

“That was - amazing,” John whispered, touching their foreheads together as he stroked along Sherlock’s jaw, “I can’t even - thank you.”

“Thank _you_ ,” Sherlock replied, licking his lips, “for allowing me to do so. It was a most enjoyable experience, though I do believe I will require repetition if I am to learn anything of use.”

John laughed hoarsely, moving his hand into Sherlock’s hair. The Mer sucked in a breath as John’s fingers glanced off his ear; surprised, John moved to pull away, only for Sherlock to turn his head and nuzzle into John’s palm.

“Can I- can I do anything for you?” John asked, fumbling; Sherlock had just given him one of the most pleasurable - if not surprising, he blushed to remember - and erotic experiences he’d ever had, but he wasn’t sure how it would work for the Mer. If Sherlock’s eyes hadn’t been keenly watching him, he would have surreptitiously glanced into the water to see if he could see - well, any indication of Sherlock’s own arousal, or something he could do to assist with it.

But he couldn’t draw his eyes away from Sherlock, and was rewarded when the Mer took a shaky breath and chuckled, nosing John’s inner thigh again. “No, I am well,” Sherlock said and the sincerity of his quirked smile filled John’s chest with blooming warmth, “While I appreciate the offer, I am afraid it would be pushing for you to give more of yourself tonight than I have already taken.”

John pursed his lips, smoothing his fingers through Sherlock’s hair in a belated attempt to tame it before the Mer tugged at his knee and hip.

“Come on,” he said, peeling John away from his position on the pier, “into the water to wash that off.”

Sherlock was as gentle as the first time he’d helped John wash off, cupping the warm water to his skin to rinse off the remnants of sweat and semen on his belly, passing his hand through the thicket of hair at his groin. The water at the end of the pier was just deep enough for John’s feet to graze the bottom, but he had to pump his arms to keep his head above the surface; Sherlock helped with that too, providing a strong anchor when John clung to him as he wiped off his grimy legs.

When he had almost finished, John took a deep breath and submerged himself under the waves to rinse his hair, and on impulse cracked open his eyes. The salt stung, despite the warmth of the water, and everything was blurred and vague in his vision - even Sherlock, who was so close. But he could make out the shine of Sherlock’s tail, the beauty of its form as it curled and beat, ridges fanned out and nearly transparent in the dark water. John clenched his eyes shut and shook his head, ruffling his hair under the water to shake loose any lingering sand, and broke the surface with a gasp.

Sherlock waited until John had wiped the water from his eyes before he drew John close, one arm around his waist to keep him steady in the water, cupping his cheek and tilting his face up for a kiss. It was chaste but sweet, a tender press of lips that they lingered over, unwilling to part.

“The moon sets soon,” Sherlock whispered against John’s lips, moving to kiss the beads of seawater from John’s cheek, “You would do well to return to your ship, if you are to depart in the morn.”

“How did you-” John began, then sighed, smiling, “Yeah, you’re right. I’m not sure how I can let you know-”

“I’ll watch over you,” Sherlock interrupted, pulling John forward again to nestle him in the crook between his jaw and chest, smoothing his hands down John’s bare back, “and I will find you again, in due time.”

“Okay,” John swallowed, listening to the beating of Sherlock’s heart under the planes of smooth muscle, a steady drum that synchronized with John’s own as he listened.

“I promise,” Sherlock said, in return; John wrapped a hand around the Mer’s nape to kiss him again, sealing the words they had spoken.

 

**Works inspired by this one:**

  * [Merlock](https://archiveofourown.org/works/1956114) by [evisionarts](https://archiveofourown.org/users/evisionarts/pseuds/evisionarts)




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